The Forbidden City, also called Zijin Cheng, is a 72-hectare palace complex in Beijing that was used by the emperors of China from A.D. 1420 to 1911. The Forbidden City served as a fortress to protect the emperor and his family. The complex consists of about 980 buildings, mainly in yellow and red colors, surrounded by a wall 10 meters high. The well guarded palace is surrounded also by a moat 3,800 metres long and 52 metres wide. Intruders were discouraged by guards in watchtowers with bow and arrows.