Line 13, which used to be known as The City Rail Line, was ironically enough only the third subway line to be built in Beijing. The western section between Xizhimen and Huoying was opened on September 28, 2002, while the eastern section from Huoying to Dongzhimen opened on January 28, 2003. Line 13 now has 16 stations and 40.5 kms of tracks in operation.
The very first trainsets used were originally built in the early 1970s for the Pyongyang Metro in North Korea, prior to its opening in 1973. Some of them were subsequently returned to China in 1998 and were used on Line 13 when it opened in 2002, until they were eventually replaced by newer carriages.