Analysis of information sources in references of the Wikipedia article "History of Beijing" in English language version.
A settlement since c. 1000 BC, Beijing served as China's capital from 1421 to 1911.
Beijing is the quintessential example of traditional Chinese city. Beijing's earliest period of recorded settlement dates back to about 1045 BC.
[Zhongdu's] walls, which were built on stamped clay and crowned with crenellated brick battlements, measured 18 miles (28km) in circumference and reached a height of 12 m (40 feet). Twelve gates gave access to the city, and there were 900 towers and three lines of moats.[permanent dead link ]