The City Wall of Xi'an
Erected during the Ming Dynasty (1638-1644), it is the world's largest and best-preserved ancient fortress. The rectangular city wall is 13.7 kilometers in circumference and has 5,984 crenels and 98 places for the garrison troops to stay in. There is a gate in each of the four sides, and each gate consists of a main tower, an embrasured watchtower, a lock tower, and a compound. The city wall is surrounded by a moat and a ring road lined with trees and dotted with pavilions and kiosks to form the huge Around-the-City Park.