# Stone wall

Stone walls are a kind of masonry construction that has been used for thousands of years. The first stone walls were constructed by farmers and primitive people by piling loose field stones into a dry stone wall. Later, mortar and plaster were used, especially in the construction of city walls, castles, and other fortifications before and during the Middle Ages. These stone walls are spread throughout the world in different forms.

## Materials

Stone walls are usually made of local materials varying from limestone and flint to granite and sandstone. However, the quality of building stone varies greatly, both in its endurance to weathering, resistance to water penetration and in its ability to be worked into regular shapes before construction. Worked stone is usually known as ashlar, and is often used for corners in stone buildings. Granite is very resistant to weathering, while some limestones are very weak. Other limestones, such as Portland stone, are more weather-resistant.

## Dimensions

Large structures are typically constructed with thick walls, such as those found in castles and cathedrals, which can reach up to 12 feet in thickness. These walls generally consist of a layered stone exterior and rubble infill.

## Examples

* The Great Wall of China, China. A grandiose 5,000 km long structure - 4,000 km across mountains, prairie and desert.
* Hadrian's Wall, Great Britain. When in 117 AD the Picts who inhabited Scotland defeated the famous XI Spanish legion, Emperor Hadrian decided to fence off his malevolent neighbours. This is how Hadrian's Wall (122-126) and then Antoninus' Wall (142-144) were first erected. The dimensions of both structures are impressive - 120 and 63 km respectively. Built of peat and stone, they are not as well preserved as many other buildings of the era.
* Aurelian's Wall, Rome, Italy. With this wall, Emperor Aurelian wanted to protect the city from invading barbarians. He was in a great hurry and the monumental structure, 19 km in circumference, 8 m high and 3.4 m thick, was built in only 5 years (271-275).
* Avila, Spain. The 12 m high and 3 m thick stone walls, 9 gates and 88 towers represent a well-preserved medieval fortress. It was built between the 11th and 14th centuries on the site of Arab and Roman fortifications.
* Essaouira, Morocco. An 18th century international design: with the help of European engineers and architects, Sultan Mohammed III Ben Abdallah created a "beautifully designed fortress", which is how the name Es-Saouira translates.
* Greater Zimbabwe, Zimbabwe. The ancient and largest sub-Saharan African city, it was built from the 11th to the 14th century and at its peak it was inhabited by some 18,000 people.
* The ramparts of Old Quebec, Canada. Europeans established their first settlement here in 1535 - it was called "canada" (in the language of the natives, "village", "settlement"). The city of Quebec came later, in 1608, but today its fortress walls are the oldest in North America.
* Sacsayhuaman, Cusco, Peru. The ancient city of Cusco resembles a puma (the sacred animal of the ruling dynasty) in outline and the six-metre high fortress walls are its "teeth".
* Castillo San Felipe de Barajas, Cartagena, Colombia. One of Colombia's Seven Wonders, the 16th century fortress is known for its walls, thick at the base and tapering at the top.