The Shenzhen Metro is the subway or underground system for the city of Shenzhen in Guangdong province, China. The system opened on 28 December 2004, making Shenzhen the sixth city in mainland China to have a subway after Beijing, Tianjin, Shanghai, Guangzhou, and Wuhan. The Shenzhen Metro currently has 5 lines, 118 stations, and of total trackage in operation. The network underwent rapid expansion prior to the 2011 Summer Universiade, opening 110 km (68.35 miles) of tracks in June 2011. Currently, there are three lines under construction.