The line is 57.024 km (35.433 mi) in length,[3] and runs entirely underground through Haidian, Chaoyang and Fengtai Districts, either directly underneath or just beyond the 3rd Ring Road.

[7] The booming economy and explosive population growth of Beijing put huge demand on Line 2, surpassing its designed capacity.

[8] On December 27, 2003, in preparation for the 2008 Summer Olympics in Beijing, Phase 1 of Line 10 started construction.

[9] On July 19, 2008, Phase I of Line 10 entered operation ahead of the opening of the Olympic Games.

Local residents, after realizing their travel to a subway station would be greatly lengthened, quickly opposed the plan.

[17] This made the late 2012 opening date for that section of Line 10 highly unlikely and was postponed to the next year.

[18] On December 30, 2012, the first section of Phase II, consisting of the southern and western sides of the loop opened.

[20] The Beijing Subway started operating express trains that ran non-stop between Songjiazhuang to Jinsong to alleviate traffic in the southeastern section of Line 10.

[21] The loop was fully enclosed on May 5, 2013 with the opening of Fengtai and Niwa stations, as well as the infill Jiaomen East.

[25][26] From Bagou near Wanliu Park in Haidian District, Line 10 runs straight east, between the northern 3rd and 4th Ring Roads.

At Xitucheng, the line meets the northern section of the Yuan dynasty earthen city wall, called tucheng.

Regular subway users can use a Yikatong card, which offers even cheaper journeys, as well as mobile phone apps, which deploy payment via a QR code.

[33] With the opening of the new depot in Songjiazhuang and the need to reduce the headway on line to decrease crowding, an additional 32 trainsets were ordered.