What materials were used to build the Pantheon? | Reference.com What materials were used to build the Pantheon? A: Quick Answer The Pantheon, a 1,900-year-old Roman temple containing the world's largest free-standing dome, is made primarily of concrete, volcanic rock and granite. The most remarkable part, the rotunda and dome, is made of concrete that includes lightweight pumice as part of the aggregate. Full Answer The Pantheon was built to honor all of the Roman gods. The structure's dome is 43 meters high, 43 meters in diameter and free-standing. The dome is attached to a granite portico, or entrance porch. The 39-foot-high gray granite portico columns, each weighing 60 tons, came from a quarry in Egypt. The stone in the rotunda is primarily volcanic or shaped concrete, honeycombed with hidden arches to add strength to the entire structure. The dome is heavier and thicker at the bottom than at the top, and the center of the dome has an 8-meter-wide opening called an oculus.

Its structure is further lightened at the top by using more lightweight volcanic rock in the concrete aggregate, with heavier granite-based concrete aggregate used toward the dome's base. This is a construction technique that is still used today. Arches are used throughout the structure to add strength without adding too much weight to the foundation. Today, nearly 2,000 years after its construction, the Pantheon still shows no signs of settling or cracking. It is still in use as a Roman Catholic church, the Santa Maria Rotonda. Pantheon in Rome might actually be a giant sundial | Daily Mail Online comments The huge 30ft hole built into the dome of Rome’s Pantheon has mystified minds for centuries. Now historians have come up with an intriguing explanation for the feature – it was built as a sundial to illuminate the emperor as he entered on important occasions. The opening is the only source of natural light for the 2,000 year-old structure, but at the same time it also lets in rain and there are tiny holes in the floor which act as a drain.

The 'oculus': Scientists believe that the 2,000-year-old Pantheon in Rome acts as a giant sundial A new study claims that the purpose of the 30ft-wide hole in its roof was to direct a beam of light to illuminate the entrance at the exact moment the emperor entered the dome Experts found that the hole allows a single shaft of sunlight to illuminate the interior during the March and September equinox as well as on April 21 – the date Rome is said to have been founded. RELATED ARTICLES Share PANTHEON - TEMPLE TO THE GODS Situated in the charming Piazza della Rotonda, the Pantheon is the most intact of all Roman structures in the Italian capital. With a graceful dome perched high above a massive circular chamber, it is lit by sunlight streaming through the 30ft hole at the dome's apex. An architectural masterpiece, no one quite knows how they rendered such a large dome from concrete. Most believe, however, that the hole in its roof is a testament to Rome's warm climate. The Pantheon - meaning 'to every god' - was commissioned as a temple to all the gods of Ancient Rome, and rebuilt by Emperor Hadrian in about 126 AD.

It has been in continuous use throughout its history and, since the 7th century, has been used as a Roman Catholic church. The emperor would have been bathed by the sun’s rays as he entered the building on these auspicious occasions. Professor Giulio Magli, from the Polytechnic of Milan, said:'The role of the Pantheon is poorly understood and it's function still remains uncertain, although we believe the sun has a significant role in the building. 'We have drawn our conclusions by studying other Roman monuments in the city including the Domus Aurea or as it is also known the Emperor Nero's Golden Palace which also had a similar domed roof. 'The sun and time were both linked architecturally in the ancient Roman period and they were used as a form of cosmological signpost for them. By bathing the Emperor in sunlight this would have a dramatic effect on him and raise him to the status of a god.' He added that their research had shown the Pantheon was strongly connected with the solar cycle during the year, and that at least one of its main functions was to associate the sun with the power of Rome and to reinforce the emperor’s divine right to rule.

The Pantheon - meaning 'to every god' - was commissioned as a temple to all the gods of Ancient Rome, and rebuilt by Emperor Hadrian in 126 AD He explained that during the darker winter months the beam illuminates only the vaulted dome. However, at noon on the equinoxes it reaches the floor and on April 21 the beam fully illuminates the entrance at midday. Building of the Pantheon was started in 27BC by Agrippa and his name is still visible over the entrance, although it was not finished until AD128 by the Emperor Hadrian. The word Pantheon means 'to every God' and during its long 2,000 year old history the building has also served as a Roman Catholic church and services are still held there. Today the Pantheon also houses the tombs of Italy's last two kings Vittorio Emanuele II and Umberto I and volunteers maintain a vigil over the royal resting places. Overview of The Roman Pantheon: The Triumph of Concrete Home · Order Book · An Overview of The Roman Pantheon... The Roman Pantheon: The Triumph of Concrete An overview of the book by David Moore, P. E.

Revealed within the pages of this source book is a clear description of the development and usage of concrete by the Romans in constructing the Pantheon and other still-existent structures, built around the time of Christ. The book contains architectural details, sections, pictures, and other features. The concrete dome of the Pantheon spans some 143 feet without the aid of metal reinforcement like modern buildings. The building even has unusual cracks and yet it still stands. The great painter Michelangelo offered one explanation: it is "angelic, and not of human design." Certainly most if not all of our modern buildings would not meet the harsh weathering of 1800 years that the Pantheon has endured and survive. This book answers many of the fundamental questions regarding the longevity of this beautiful structure and shows how modern concrete construction is just now learning to apply some of the same technologies used by the Romans. History and People There is much more to this monumental structure, built originally by the Romans as a temple, than first meets the eye. A shocking discovery is that the building is made of ancient concrete resting on unstable blue clay. On the surface, at least, this structure appears to violate all modern building codes and should have fallen down hundreds of years ago.

What is this concrete and how was it molded into such a beautiful, massive structure? This book focuses on the concrete Rome used in many of the structures that are still extant today. The Romans did not have Portland cement nor concrete mixers, so how did they make such long lasting concrete? The Pantheon required enlightened technology to erect a building some 143 feet high using only hand tools. Who were the Roman engineers? What were their design standards, their instruments, and their technical education which could make this feat possible? Lime and Kilns Lime is one of the first man-made products relying on chemical reaction - paralleling that of the manufacturing of ancient clay jars for food storage. The Romans produced lime by burning limestone pieces in a crude kiln. As a slurry, lime was applied to protect the earthen walls of ancient houses. When mixed with volcanic ash (pozzolan) and water, it becomes a mortar that the Romans used to build rock walls. The Romans later discovered how to mix this mortar with small stones, bricks, and other materials to produce concrete. Quality control of the limestone raw material, processing temperature and hydraulic reaction in the mortar are viewed through the eyes of the Roman.

Romans mastered this chemical processing and manufacturing technology to such an extent that the Pantheon, which is fundamentally a large concrete structure, is still with us today. Clay Products Clay jars, bricks, and tiles came from the dawn of civilization. The Romans focused on the extensive use of these products to enhance their lifestyle by constructing magnificent brick and clay buildings. Strangely, one source of concrete mortar for building Rome came from a mixture of wet lime and crushed pottery. Vitruvius, a Roman architect, said this was so. This book verifies his claims by examining the chemistry and reactions involved in these materials. The ingenious Romans used brick to form archways over wall openings. It was strong and worked well. Brick also covered the exterior of buildings. Identifying Roman Concrete Scientists have long known about the components of Roman concrete: wet lime and volcanic ash covering a layer of small rocks. This is a simple composite concrete. But how did it become so hard and durable to last 1800 years in the Pantheon? Where was it found? How was it placed? What did the ancients write about the materials and processes? These challenging questions are answered in Roman literature and quoted in the book for the reader.

Modern viewpoints are also included from archaeological studies to bring together this investigation. Pozzolan-Lime Behavior Perhaps the most difficult part of the research for this book was tying Roman concrete to its modern counterpart. The explanation includes an examination of the atomic structure, x-ray analysis, and scientific formulas. Surprisingly, the U.S. Bureau of Reclamation devised a roller compacted concrete (RCC) that closely resembles the chemical and material content and manufacturing method used in Roman concrete 2000 years ago! RCC is an excellent, durable concrete of interest to road building engineers and others in the engineering field. Ancient Roman Technology The Romans built many beautiful, massive structures, unusual for any period in history. Pictures and sketches of typical buildings are included showing a collective, brilliant intelligence in action in the ancient world. What was their technology? Who made up the labor force for this awesome construction feat? What were their tools and lifting devices as related to our modern types? Fortunately, we have obtained pictures. Some of these same tools served Christ Jesus in his days as a carpenter.

Some of the topics examined in the book are: metallurgy to make iron hammers and weapons; material procurement, including shipping; scaffolding to reach high walls; concrete mortar for construction; construction of foundations, walls and domes; connecting devices such as wooden pins to make long bridges possible. By this technology, the famous Pantheon was built to last the ages. Copyright © 1999 David Moore, PE BUILDING BIG: Databank: Pantheon Materials: Concrete, brick Architect: Hadrian When Roman Emperor Hadrian decided to build a monument to reflect the power of his empire, he built a dome -- but not just any dome. Hadrian constructed a building out of bricks and concrete with a dome that was bigger and more extraordinary than anything anyone had ever seen before. The enormous building, called the Pantheon, was built as a temple to all the Roman gods almost 2,000 years ago. It still exists today, almost entirely in its original form. Click photo for larger image. The Pantheon is remarkable for its size, its construction, and its design. The enormous dome stretches 142 feet in diameter; that's the same as the distance from the Statue of Liberty's sandals to her torch!

Given the dome's size and weight, Hadrian's engineers had to find ways to lighten the heavy structure. They scooped out 140 waffle-like depressions, called coffers , in five rows around the dome's base to eliminate some masonry and reduce the dome's weight. They also carved an opening, called an oculus, at the top of the dome, which reduced some mass and created a daily light show for which the Pantheon is famous. The result was an impossibly huge dome, one that would remain the world's largest for 1,300 years. Here's how this dome stacks up against some of the biggest domes in the world. (diameter, in feet) The Pantheon - Rome The Pantheon - Rome Click to Print This Page Almost 2000 years old and virtually intact, the Pantheon in Rome stands as testament not only to the engineering skill of an Empire that accelerated the development and application of concrete, but also to the durability of concrete as a sustainable construction material. The Pantheon (“Temple of all the Gods”) was originally built as a temple to the seven deities of the seven planets in the state religion of Ancient Rome.

Built of concrete, it has been in continuous use throughout its history, and is the best preserved of all Roman buildings. The Pantheon’s massive portico, consisting of three rows of eight columns, leads to the rotunda, upon which rests the building’s most distinctive feature – its 43.2m-domed concrete roof. In order to support the dome, eight-barrel vaults in the massively thick 6.4m rotunda wall carry its downward thrust. In the absence of steel reinforcing, the dome’s weight was minimised through several design features. The dome is configured as five rows of 28 square coffers that diminish in size as they approach the central 8.7m diameter opening (oculus) at the top of the dome. The coffers not only enhance the aesthetic of the building, but more importantly they reduce the thickness and therefore the weight of the concrete dome. At its base the concrete dome is more than 6m thick, but diminishes to about 1.2m at the edge of the oculus. Also crucial to the dome’s reduced weight are the variances in the type of concrete.

Towards the oculus, unglazed to further reduce the dome’s weight, a much less dense concrete mix was used containing a relatively light pumice aggregate. While the Romans cannot be credited with the invention of concrete, an honour belonging to the Egyptians, they were certainly instrumental in its large-scale uptake. This adoption is based upon the use of volcanic ash from near Pozzuoli, which when combined with lime resulted in a concrete far stronger than anything previously produced. Pozzolanic cement, as the material became known, quickly established itself as a core construction material in all large-scale Roman construction projects. The theatre at Pompeii, built in 75 BC relied heavily on concrete, as did the Colosseum, built around AD 82. As the largest and most iconic of Roman amphitheatres, the Colosseum made use of dense concrete in its foundations, as well as lightweight concrete in its numerous arches and vaults. Hundreds of examples of Roman structures made using concrete still stand today, ranging from magnificent temples and sporting arenas, to functional bridges, aqueducts, reservoirs and sewers. There are even instances of the underwater use of concrete in Roman breakwaters.

Their continued existence today embodies not only the enterprise and innovation of their creators, but also the long-term durability of concrete. Concrete technology has undoubtedly developed over the centuries, but it is not a coincidence that the designers of Te Papa, New Zealand’s national museum, chose concrete as its structural material to achieve a 350-year expected life without significant maintenance. The Pantheon – Rome – 126 AD | Monolithic Dome Institute The Pantheon – Rome – 126 AD Freda Parker • Published A temple to all gods An ancient classic Michelangelo (1475-1564) looked at everything with an artist’s critical eye, and he was not easily impressed. But when Michelangelo first saw the Pantheon in the early 1500s, he proclaimed it of “angelic and not human design.” Surprisingly, at that point, this classic Roman temple, converted into a Christian church, was already more than 1350 years old. What’s even more surprising is that the Pantheon, in the splendor Michelangelo admired, still stands today – another 500 years after he saw it. In truth, no one knows the Pantheon’s exact age.

One legend says that the first Roman citizens built the original Pantheon on the very site where the current one still stands in the Campo Marzo – modern Rome’s business district. The ancients constructed this first Pantheon after Romulus (753-716 BC), their mythological founder, ascended to heaven from that site. They dedicated it to Romulus and some of his divine ancestors and, for centuries, held rites and processions there. Most historians, however, claim that Emperor Marcus Vipsanius Agrippa built the first Pantheon in 27 BC, a rectilinear, T-shaped structure, 144 feet by 66 feet (44m x 20m), with masonry walls and a pitched timber roof. It burned in the great fire of 80 AD, was rebuilt by Emperor Domitian, but was struck by lightening and burned again in 110 AD. An elegant emperor Seven years later, Hadrian, the adopted son and successor of Emperor Trajan, became Rome’s ruler. Hadrian was elegance personified. He was tall and strong, had his hair curled and his full beard groomed daily.

Moreover, Hadrian saw himself as a divinely inspired poet, with an avid interest in Hellenic culture, especially literature, music and architecture – so much so that his contemporaries snidely called him “the Greekling.” By 120 AD, Hadrian began designing a Pantheon reminiscent of Greek temples and far more elaborate than anything Rome had yet seen. His plans called for a structure with three main parts: a pronaos or entrance portico, a circular domed rotunda or vault, and a connection between the two. The rotunda’s internal geometry would create a perfect sphere, since the height of the rotunda to the top of its dome would match its diameter: 142 feet (43.30 m). At its top, the dome would have an oculus or eye, a circular opening, with a diameter of 27 feet (8.2m), as its only light source. Hadrian said, “My intentions had been that this sanctuary of All Gods should reproduce the likeness of the terrestrial globe and of the stellar sphere…The cupola…revealed the sky through a great hole at the center, showing alternately dark and blue.

This temple, both open and mysteriously enclosed, was conceived as a solar quadrant. The hours would make their round on that caissoned ceiling so carefully polished by Greek artisans; the disk of daylight would rest suspended there like a shield of gold; rain would form its clear pool on the pavement below, prayers would rise like smoke toward that void where we place the gods.” Hadrian visualized himself enthroned directly under the Pantheon’s oculus – a near-deity around whom not only the Roman empire but the universe, the sun, and the heavens obediently revolved. Work begins Hadrian’s engineers began clearing the site and preparing the foundations. They dug a circular trench 26 feet (8 m) wide and 15 feet (4.5 m) deep for the rotunda’s foundation and rectangular trenches for the pronaos and the connector. They lined the trenches with timber forms and layered those with pozzolana cement – a powerful cement that the Romans discovered they could make by grinding together lime and a volcanic product found at Pozzuoli, Italy. Though the Romans had been building with concrete since about 200 BC, work on the Pantheon was difficult and proceeded in gradual stages.

Other buildings surrounded the site so laborers lacked space in which to work. They also lacked machinery. Vitruvius (cir. 20 BC), a noted Roman architect, recorded the process followed in his day, that was probably still used by the Pantheon’s builders. The ancients hand mixed wet lime and volcanic ash in a mortar box, adding very little water so that they got a nearly dry composition. They carried this mixture to the jobsite in baskets and poured it over a prepared layer of rock pieces. They then tamped the mortar into the rock layer. The tamping packed the mortar, reduced the need for excess water, but, at the same time, stimulated bonding. Transportation presented another problem. Just about everything had to come down the Tiber by boat, including the 16 gray granite columns Hadrian ordered for the Pantheon’s pronaos. Each was 39 feet (11.8 m) tall, five feet (1.5 m) in diameter, and 60 tons in weight.

Hadrian had these columns quarried at Mons Claudianus in Egypt’s eastern mountains, dragged on wooden sledges to the Nile, floated by barge to Alexandria, and put on vessels for a trip across the Mediterranean to the Roman port of Ostia. From there the columns were barged up the Tiber. A concrete dome Eventually, work began on the concrete dome, constructed in tapering courses or steps that are thickest at the base (20 feet) and thinnest at the oculus (7.5 feet). The Romans used the heaviest aggregate, mostly basalt, at the bottom and lighter materials, such as pumice, at the top. They embedded empty clay jugs into the dome’s upper courses to further lighten the structure and facilitate the concrete’s curing. In the dome’s construction, the Romans probably used temporary wooden centering on which they layered concentric rings of masonry and concrete. Through the ages, engineers have theorized about the centering. Some say the Romans used heavy wooden scaffolding, throughout the construction process, that reached from the floor to the oculus.

Others believe that centering was not required for the lower third of the dome, so the Romans used a lighter centering system supported from the dome’s interior, second cornice line. To create the dome’s oculus, which acts as a compression ring, the Romans built two circles of bipedales, handmade bricks that were 23.4 inches (60 cm) square and 1.56 inches (4 cm) thick. They laid the bipedales edgewise in three vertical courses, then circled the oculus with a bronze cornice. The oculus was not the only feature that got a bronze treatment. Hadrian had the original roof bronze-tiled and the Latin lettering on the entablature inscribed in bronze. It read: M AGRIPPA L F COS TERTIUM FECIT, which translates to “Built by Marcus Agrippa, the son of Lucius, third counsul.” An enduring mystery Why the egotistical Hadrian insisted on crediting his predecessor for the Pantheon remains an unsolved mystery. Some believe he did it as a symbolic gesture that reinforced his connection to Rome’s ancient imperial line. But the Pantheon presents yet another, far greater mystery.

Why, after nearly 2000 years, is this structure, built on marshy land, with a dome whose span was not surpassed for hundreds of years, still standing? Theories abound. Some believe the Pantheon is divinely protected. Until the 5th century, it was a temple dedicated to all the Roman gods. In 609, Emperor Phocas gave it to Pope Boniface IV, who consecrated it, dedicated it to St. Mary and all the Christian martyrs, and renamed it Santa Maria ad Martyres. While the Pantheon may be divinely protected, there are more earthbound reasons for its survival as well. It was built of a very strong concrete with pozzolona cement. A gradation process was used so that the structure is heavier at the bottom and much lighter at the top. The dome’s oculus or opening lightens the load and acts as a compression ring. Whatever the reasons, the Pantheon is the only structure of its age, size and span that has successfully survived the scourge of time and gravity and has come down to us, intact, and in all its splendor and beauty.

Like Michelangelo, we too can look at the Pantheon and marvel at this wonder that looks more like the work of angels, not humans. Reference Sources: Illustration by David A. CollinsBuilt: 120-126 AD under Emperor Hadrian Foundation: 24’ thick at base and steps to 21’ at ground level Rotunda: concrete, 20’ thick; 142’ diameter Oculus: concrete: 7.5’ thick; 27’ diameter Interior Columns: 3’ diameter, 29’ tall topped with a corinthian capital of 4’ totaling 32’ 9" tall, 25 tons each Portico: 16 granite columns 39’ tall, 5’ diameter, 60 tons each The Monolithic Dome and The Pantheon Monolithic’s President David South says that in building Monolithic Domes we have three major advantages the Pantheon’s builders simply did not have: Airforming – The Romans created the Pantheon’s form with earthworks and timber – an arduous, time-consuming process. We can inflate a giant Airform in less than two hours.

The Airform has the additional advantages of being portable and ultimately becoming the roof membrane of the finished structure. Concrete – The Pantheon’s concrete was a mixture of pozzolan, lime and a small amount of water. That mixture was tamped – not poured – into place. Today, we have portland cement, which is easily ten times stronger and much easier to work with. Rebar – All concrete is weak in tension. We strengthen our concrete with reinforcing steel (rebar). The Romans did not have that option. They used ropes of vitreous china for reinforcement. To further compensate for the weakness and weight of the concrete, the Romans built extremely thick footing and drum walls. Otherwise, the weight of the dome would have spread the vertical walls of the drum and the Pantheon would not have lasted. Note: Reprinted from our Summer 2001 Roundup. Pantheon – 17th Century — This drawing by Giovanni Battista Falda dates back to the late 17th century. The Pantheon was defined as a temple to all gods. Pope Urban VIII (1623-1644) added the two bell towers designed by Bernini. They were removed in 1833.

Visitors from all over the world visit the Pantheon, one of the oldest intact buildings of antiquity. Pantheon Dome | Engineering & Technology | Video | PBS LearningMedia Background Essay The Pantheon Dome, completed in 128 A.D., was one of the most impressive engineering accomplishments of its time -- indeed, for all time. Although Romans had been building small domed bathhouses and temples for centuries, no other dome would match the Pantheon Dome's 143-foot diameter for another 15 centuries. The dome was constructed primarily of concrete, a material rarely used at that time for anything besides foundations. This allowed workers to more easily taper the thickness of the dome walls, which ranges from 5 feet near the top to more than 20 feet where the dome meets the building's vertical walls. Another impressive feature of the Pantheon Dome is the oculus, or "eye", which provides a 27-foot opening to the sky. The oculus is located 143 feet above the building's floor, making the dome as high as it is wide. The Pantheon's completion was certainly a crowning achievement for its designer, Hadrian, the 13th emperor of Rome.

It did, however, present its share of engineering problems. Most important of these was that the dome required significant lateral support in the form of enormous concrete "step rings" near where the elegantly arching dome meets the vertical walls of the lower part of the building. Throughout most of a dome, inward and upward forces counteract the force of gravity -- the weight of the dome itself. These opposing forces cause the individual sections of the dome to push hard against, or compress, one another. Where compression is high, the dome is stable. At the lower sections, where the dome meets the building's vertical walls, however, the necessary compressive force is missing. To save the dome from collapse, Pantheon engineers placed the massive concrete step rings around the base of the dome. These rings are heavy enough to resist the outward force of the dome and have kept the dome stable and relatively free from cracks for nearly 2,000 years. The Secrets of Ancient Rome’s Buildings | History | Smithsonian The Secrets of Ancient Rome’s Buildings What is it about Roman concrete that keeps the Pantheon and the Colosseum still standing? The Colosseum, inaugurated in A.D.

80, seated 50,000 and hosted gladiatorial games, ritual animal hunts, parades and executions. (Tiziana Fabi / AFP / Getty Images) smithsonian.com November 16, 2011 The Romans started making concrete more than 2,000 years ago, but it wasn’t quite like today’s concrete. They had a different formula, which resulted in a substance that was not as strong as the modern product. Yet structures like the Pantheon and the Colosseum have survived for centuries, often with little to no maintenance. Geologists, archaeologists and engineers are studying the properties of ancient Roman concrete to solve the mystery of its longevity. “Roman concrete is . . . considerably weaker than modern concretes. It’s approximately ten times weaker,” says Renato Perucchio, a mechanical engineer at the University of Rochester in New York. “What this material is assumed to have is phenomenal resistance over time.” That resistance, or durability against the elements, may be due to one of the concrete’s key ingredients: volcanic ash. Modern concrete is a mix of a lime-based cement, water, sand and so-called aggregates such as fine gravel.

The formula for Roman concrete also starts with limestone: builders burned it to produce quicklime and then added water to create a paste. Next they mixed in volcanic ash—usually three parts volcanic ash to one part lime, according to the writings of Vitruvius, a first-century B.C. architect and engineer. The volcanic ash reacted with the lime paste to create a durable mortar that was combined with fist-size chunks of bricks or volcanic rocks called tuff, and then packed into place to form structures like walls or vaults. By the beginning of the second century B.C., the Romans were already using this concrete in large-scale construction projects, suggesting their experimentation with the building material began even earlier. Other ancient societies such as the Greeks probably also used lime-based mortars (in ancient China, sticky rice was added for increased strength). But combining a mortar with an aggregate like brick to make concrete was likely a Roman invention, Perucchio says. In the earliest concretes, Romans mined ash from a variety of ancient volcanic deposits. But builders got picky around the time Augustus became the first Roman emperor, in 27 B.C.

At that time, Augustus initiated an extensive citywide program to repair old monuments and erect new ones, and builders exclusively used volcanic ash from a deposit called Pozzolane Rosse, an ash flow that erupted 456,000 years ago from the Alban Hills volcano, 12 miles southeast of Rome. The Pantheon, a temple to the gods, was completed in A.D. 128. The temple's dome is still the largest unreinforced concrete dome in the world. (Guido Bergmann / Bundesregierung-Pool via Getty Images) The Colosseum, inaugurated in A.D. 80, seated 50,000 and hosted gladiatorial games, ritual animal hunts, parades and executions. (Tiziana Fabi / AFP / Getty Images) The Tomb of Caecilia Metella, daughter of a Roman consul. This 1841 daguerreotype is one of the earliest known photographs of Italy. (SSPL / Getty Images) The dome of Tempio di Venere e Roma, a temple dedicated to two goddesses and inaugurated by Emperor Hadrian in A.D. 135.

(Tiziana Fabi / AFP / Getty Images) “Emperor Augustus was the driving force behind the systemization, standardization of mortar mixes with Pozzolane Rosse,” says Marie Jackson, a geologist and research engineer at the University of California at Berkeley. Roman builders likely favored the ash deposit because of the durability of concrete made with it, she adds. “This was the secret to concretes that were very well bonded, coherent, robust materials.” Jackson and her colleagues have been studying the chemical composition of concretes made with Pozzolane Rosse. The ash’s unique mix of minerals appears to have helped the concrete withstand chemical decay and damage. The Romans favored another specific volcanic ash when making concrete harbor structures that were submerged in the salty waters of the Mediterranean. Pulvis Puteolanus was mined from deposits near the Bay of Naples. “The Romans shipped thousands and thousands of tons of that volcanic ash around the Mediterranean to build harbors from the coast of Italy to Israel to Alexandria in Egypt to Pompeiopolis in Turkey,” Jackson says. Seawater is very damaging to modern concrete.

But in Roman concrete, the Pulvis Puteolanus “actually plays a role in mitigating deterioration when water percolates through it,” Jackson says. Although the exact mechanism is unknown, it appears that chemical reactions among the lime paste, volcanic ash and seawater created microscopic structures within the concrete that trapped molecules like chlorides and sulfates that harm concrete today. Despite the success of Roman concrete, the use of the material disappeared along with the Roman Empire. Concrete structures were seldom built during the Middle Ages, suggesting volcanic ash wasn’t the only secret to the durability of Roman concrete, Perucchio says. “These really large projects could only be done with the appropriate bureaucracy, with the proper organization that the Roman Empire would provide.” Erin Wayman is an assistant editor at Smithsonian and writes the Hominid Hunting blog. Like this article? Pantheon - Ancient History Encyclopedia Pantheon by Mark Cartwright published on 12 June 2013 The Pantheon is the best preserved building from ancient Rome and was completed in c. 125 CE in the reign of Hadrian .

Its magnificent dome is a lasting testimony to the genius of Roman architects and as the building stands virtually intact it offers a unique opportunity for the modern visitor to step back 2,000 years and experience the glory that was Rome. Function & Dedication The purpose of the building is not known for certain but the name, porch and pediment decoration suggest a temple of some sort. However, no cult is known to all of the gods and so the Pantheon may have been designed as a place where the emperor could make public appearances in a setting which reminded onlookers of his divine status, equal with the other gods of the Roman pantheon and his deified emperor predecessors. Remove Ads Advertisement The Pantheon was built on the exact site of two earlier Pantheon buildings, one commissioned by Marcus Vipsanius Agrippa (27-25 BCE) and the second by Domitian . The first was destroyed by fire in 80 CE and the second was struck by lightning in 110 CE and again burned down. The third Pantheon was probably begun in the reign of Trajan (98-117 CE) but not finally finished until around 125 CE when Hadrian was emperor.

Following Hadrian’s usual practice of dedicating rebuilt buildings and monuments in honour of the original dedicator, the Pantheon is dedicated to Marcus Agrippa and the prominent inscription on the porch façade reads: M. AGRIPPA L.F. COS TERTIUM FECIT (Marcus Agrippa, son of Lucius, three-time consul , made this). Below the main inscription is a smaller one indicating the restorations carried out by Septimius Severus and Caracalla in 202 CE and reads: pantheum vetustate corruptum cum omni cultu restituerunt (with every refinement they restored the Pantheum, worn by age). Exterior The whole building stands on a 1.3 m high base which originally extended a further 7 metres in front of the colonnade. Steps in Numidian yellow marble extended from the outer ends of this base. The building consists of two principal parts - the porch, which is very Classical Greek in presentation, and the circular main building which is much more Roman in style and reminiscent of the architecture of the large Roman baths . The circular building is built with brick and concrete but was originally faced with white marble stucco to match the porch in appearance.

The dome is concrete with the external surface originally covered in sheets of bronze but these were removed by Constans II in 663 CE. Remove Ads Advertisement The porch measures 33.1 x 13.6 m and presents a front colonnade of eight Corinthian columns 11.8 m high. The monolithic column shafts are in Mons Claudianus and Aswan grey granite with the bases and capitals in white Pentelic marble. The pediment above the columns is now empty but drill holes suggest there was originally an emblem of some sort, possibly an eagle or wreath which would have been in gilded bronze and symbolised Jupiter . The porch was faced with white Pentelic marble and is decorated with reliefs showing objects used in religious sacrifices (such as dishes, boxes and axes), garlands and candelabras. The interior of the porch measures 34 x 20 m and has four rose-pink columns creating three aisles. The pavement is restored but reflects the original design with grey granite rectangles and circles in white marble. The interior of the porch was also panelled with marble but this has since been lost, revealing the brickwork.

Interior The Pantheon may well be the first building from Classical architecture where the interior is deliberately made to outshine the exterior. The circular part of the building or rotunda was entranced via two bronze doors measuring 12 x 7.5 m (those of today are ancient but not original). The rotunda measures 43.2 m in diameter which is exactly the maximum height of the dome, itself a perfect hemisphere. At the very top of the dome is an opening to the sky (oculus) which is 8.8 m in diameter and has a decorative bronze sheet frieze. The dome is made from a light tufa and scoria (a type of pumice) mix of concrete (caementa) and its interior is further lightened by five rings of 28 coffers which reduce in size as they rise towards the centre of the dome. These may have been originally covered in bronze sheets. The wall of the rotunda is 6 metres thick and has seven alcoves which are alternatively semi-circular (3) and rectangular (4). The alcove opposite the door is the most impressive and reaches the ceiling.

It has a decorative red porphyry frieze and cornice and is flanked by two Corinthian marble columns of Phrygian purple. Each of the other alcoves has two marble columns in Phrygian purple (semi-circular) or Numidian yellow (rectangular). Each alcove also had three niches for statues and a small window with another seven windows placed around the rotunda walls. The pavement is the original and consists of a square pattern using grey granite, red porphyry, Numidian yellow and Phrygian purple marble.

Question: What material was used in making the 2,000 year-old dome of the Pantheon in Rome?
Answer: Concrete