Saalburg The Saalburg is a Roman fort located on the Taunus ridge northwest of Bad Homburg , Hesse , Germany . It is a Cohort Fort belonging to the Limes Germanicus , the Roman linear border fortification of the German provinces . The Saalburg , located just off the main road roughly halfway between Bad Homburg and Wehrheim is the most completely reconstructed Roman fort in Germany . Since 2005 , as part of the Upper German " limes " , it forms part of a UNESCO World Heritage site . In the modern numbering system for the " limes " , it is ORL 11 . History of Research . The earliest examinations of the site were undertaken from 1853 to 1862 by the Nassau Antiquarian Society under the direction of Friedrich Gustav Habel ( 1793 – 1867 ) . But the great impulse to provincial Roman archaeology in Germany came in 1892 , when the " Reichs - Limes - Kommission " ( the Imperial Commission for the Roman borders ) , then chaired by Theodor Mommsen began to research the course of the Limes Germanicus in its entirety , as well as the location of all its forts . In the course of this enormous project , not completed for decades , intensive exploration of the Saalburg and its surroundings was pursued by the archaeologists charged with this stretch of the " limes " , Louis Jacobi ( 1836 – 1910 ) and his son and successor Heinrich Jacobi ( 1855 – 1946 ) . In 1897 , Kaiser Wilhelm II , following a suggestion by L . Jacobi , ordered the reconstruction of the Saalburg fort according to the detailed results of its excavation . As a result , the Saalburg became the most completely reconstructed fort on the entire " limes " . It also houses the Saalburg Museum , one of the two most important institutions dedicated to the study of the German Limes ( the other being the Limesmuseum of Aalen ) . From 1967 to 1993 , the museum was directed by the well - known archaeologist Dietwulf Baatz , whose many publications fostered a broad interest in provincial Roman archaeology well beyond specialist circles . Location . Since prehistoric times , trade routes like the " Lindenweg " or " Linienweg " connected the Rhine - Main plain with the Usingen basin , which had been a centre of population since the Neolithic . Such routes would have followed a course from the mouth of the Nidda near Höchst , northwards across the low Taunus ridge , as does the modern Bundesstraße 456 . A location along major communication routes almost always equals a strategic importance . Thus , it is no surprise that the mountain pass beside the Saalburg was first fortified by Roman troops during Domitian ' s wars against the Chatti ( AD 81 - 96 ) , when two simple earthen enclosures were erected ( " Schanzen " A and B , located between the restored fort and the modern road ) . The Fort . History . Shortly after the two enclosures , around AD 90 , a simple wood - and - earth fort was built to house a " numerus " . A " numerus " was a unit of auxiliary troops consisting of 2 " centuriae " and numbering about 160 men . There is some evidence that the troop stationed at this fort was a " numerus Brittonum " , i . e . a unit from Britain , but this is not entirely clear . Late in the reign of Hadrian , c . AD 135 , the " numerus " fort was replaced with a much larger ( 3 . 2 hectare ) fort for a cohort , a unit of about 500 men . The new castle was reoriented to face the growing Roman city of Nida ( now Heddernheim ) . Originally , it had dry - built wood - and stone walls , which were replaced in the 2nd half of the 2nd century with mortared stone walls and an earthen ramp ( 147 x 221 m ) . The reconstructed fort is based on that third and last architectural phase , but reminders of the second phase are visible in the " retentura " ( the back of the fort ) . Part of the second - phase defensive ditch has also been restored and can be inspected there . The cohort fort was occupied by the " Cohors II Raetorum civium Romanorum equitata " ( 2 . partially mounted Raetian cohort with Roman citizenship ) , a partially equestrian 500 - men infantry unit , probably under the command of the legionary headquarters at Mogontiacum ( modern Mainz ) . The cohort had initially been stationed at " Aquae Mattiacorum " ( Wiesbaden ) , had then been moved to the Butzbach fort ( ORL 14 ) and finally to the Saalburg . The fort existed in that form and with that occupancy until the fall of the German " limes " in c . AD 260 . During the intervening period , the name of the unit is repeatedly mentioned in stone inscriptions , as are the names of some of its commanders . In the early 3rd century , the situation along the limes became increasingly unsettled . A preventative war under Caracalla , who marched against the Alamanni and their Chatti allies from Raetia and Mogontiacum in AD 213 , lowered the Germanic pressure on the border only temporarily . The town of Nida ( capital of the regional " civitas " ) was given a defensive enclosure around that time . Already around 233 , the Alemanni entered Roman territory again ; further major incursions took place in 254 and 260 . Eventually , all areas east of the Rhine were lost during the major political and economic crisis of the mid 3rd century . In the course of these events , the Saalburg fort appears to have been abandoned deliberately and without military action . After the abandonment of the Upper Germanic Limes , the fort was used as a quarry . Archaeology , architecture . The Saalburg in its final architectural phase , in the form reconstructed today , as a cohort fort typical for this part of the limes , a 147 by 221 m rectangle with 4 gates . The 3 . 25 m interior was enclosed by a double ditch and a mortared defensive wall ; its external face was whitewashed and painted with a trompe - l ' œil pattern of ashlar blocks . On the inside , an earthen ramp was placed along the length of the wall , to enable defenders to access the top . The corners were rounded and not crowned with towers , but all four gates were flanked by two towers each . The fort was oriented in such a way that its main gate , or " porta praetoria " faced south - south - east , that is away from the " limes " but towards Nida . The central structure of the fort was a large " principia " , a central plaza surrounded by housing or offices for the higher officers , which was flanked by a roofed hall for assemblies of the fort ' s garrison . The " praetentura " ( front part of the fort ) contained the " praetorium " ( the fort commander ' s residence ) to the west of the " via praetoria " , and a large " horreum " ( grain store ) to its east . The rest of the fort ' s interior , today a park - like area of grass and trees , should be visualised as packed with further buildings : stables , magazines , workshops and , of course , the actual troop quarters , subdivided into contubernia . Two such troop barracks have been reconstructed in the southeast part of the fort . For the general arrangement and terminology of Roman fort architecture , see Castra . Vicus . The Saalburg is not only the most consistently reconstructed " limes " fort , it is also the only one to have had its vicus ( adjacent civilian settlement ) partially excavated and preserved . The parts of the vicus visible today are located mostly to the south of the fort , on both sides of the road that linked it with Nida , the regional capital and base of further garrison behind the border . The village begins immediately outside the main gate , where the ruins of a mansio ( an official hostel ) and , behind it , of a bath for the soldiers were found . These are followed along the road by the preserved basements and foundations ( partially reconstructed ) of residential houses and of - as believed in the time of the excavations - a mithraeum , a shrine to the Mithras , a deity popular among the Roman army . The fort ' s bath was relatively large and quite elaborately designed to have all the main features of Roman Thermae . It has an " apodyterium " ( changing room ) , a " frigidarium " ( cold bath ) , two " tepidaria " ( lukewarm baths ' , a " caldarium " ( hot bath ) and a " sudatorium " ( sauna ) . The complex was heated from the " praefurnia " ( firing places ) ; and all rooms except the " apodyterium " and " frigidarium " were served by a hypocaust system ( underfloor and wall heating ) . Archaeologists assume that the overall complex ( fort and vicus ) housed a population of up to 2 , 000 ( 500 soldiers , 1 , 500 civilians ) . Saalburg Museum . Although the Saalburg is mainly known as an archaeological park and museum , it also serves a number of scientific functions less obvious to the visitor . The most striking features for the modern visitor are the fully reconstructed walls and gates , the " principia " with its " aedes " ( shrine containing the " signa militaria " or standards ) , the assembly hall , the " horreum " ( provisions store ) , the two barracks buildings with their reconstructed interior " contubernia " and the partially rebuilt " praetorium " . The " horreum " contains an informative exhibition , focusing on cultural , historical , architectural , and military aspects of Roman Germania . The museum exhibits a large collection of well preserved military and domestic equipment from the Saalburg and other sites in the area , as well as a series of architectural and terrain models . Beyond this , the Saalburg has , since its reerection , also functioned as an internationally renowned centre of research , concerned with provincial Roman archaeology in general , and the " limes " in particular . The heart of this centre is a specialised library of 30 , 000 volumes and 2 , 200 slides . The " Saalburgmuseum " regularly organises colloquia and has its own series of academic publications . Since the 1980s , the Saalburg is also the venue of occasional Classical concerts . Surroundings . Only about 200 m north of the " porta decumana " ( back gate ) , the " limes " runs by in a west - easterly direction . Part of the border defense ( ditch , bank and palisade ) has been reconstructed here . As along most of its extent in the Taunus area , the " limes " near the Saalburg is remarkably well preserved and can be easily followed through the landscape . Ditch and bank are distinctly visible for long stretches , and many of the former watch towers have been partially preserved or are visible as small mounds . Thus , the Saalburg is a good starting point for further exploration of the " ' limes " . The Saalburg in the context of the local limes " " ' between the " Kleinkastelle " ( small forts ) of Heidenstock to the southwest and Lochmühle to the northeast : Near the Saalburg , a copy of the " Jupitersäule " ( a type of painted tall sandstone stele dedicated to Jupiter and common in the German provinces ) of Mainz has been erected . Saalburgbahn . The reerection of the fort in the late 19th and early 20th century led to a surge of interest by the local population , including visitors using the spa at Bad Homburg . To provide comfortable access , the Bad Homburg tram company constructed a direct rail link , the " Saalburgbahn " . After a pre - World War I flourish , the company was badly affected by post - war inflation and a massive drop of visitor numbers to the spa . Eventually , the service was closed ; scanty traces of its embankment and the ( closed ) station remain . Today , the fort can be reached by an hourly bus link from Bad Homburg .