The City Walls, ramparts, gates and watchtowers form one of the oldest and most complete city defences still around. Built in the 13th century on the foundations of the original Tang Forbidden City surrounding the city centre you can walk, rent a bike or take an electric cart around the full 14km circuit, with great views of the city on either side.
The Tang dynasty built its capital Chang'an 7km/4.5 miles north-west of where Xi'an lies today. Its defensive walls, 22km/14 miles in length, formed an irregular quadrilateral with twelve gates, each with three entrances. The main gate was reserved for the use of the emperor. The north side of the wall is shaped rather like the Ursa Major constellation, and the south side like Ursa Minor.
The town was served by eight main streets and 160 side streets together with large numbers of palaces (none of which survive) and an excellent drainage and sewage system using pentragonal clay pipes. On the excavation site, in addition to the remains of the town walls to the south-west, the visitor can still see a large mound of earth which is all that is left of the Han imperial residence, the Palace of Weiyang, around which countless legends have been woven.