Underground Project 131, Military tunnel complex in Xianning, China

Underground Project 131 is a tunnel system carved into a mountain in Hubei province with different functional areas. The facility includes meeting rooms, offices, and communication centers built into the rock.

On 31 January 1969, China decided to build an underground PLA command headquarters as Sino-Soviet tensions raised the risk of nuclear war; the code name 131 comes from that date. General Huang Yongsheng oversaw construction of 456 metres of tunnels with meeting rooms, a communications centre and offices for Mao Zedong and Lin Biao, plus surface villas. After Lin Biao's death and Huang's arrest in September 1971, work stopped; neither man ever visited.

Signs at the site call it Chengshuidong Tourist Area, and the tunnel rooms are labelled with their intended functions: meeting rooms, offices for Mao Zedong and Lin Biao, and a communications centre. Surface pavilions hold Mao badges, posters and maps of China's military history. Huang Yongsheng, who led construction, is buried on the grounds.

Some areas of the tunnel system are open to visitors and display exhibits about military history. Keep in mind that certain zones may be restricted for international tourists, and it is wise to check access rules in advance.

The facility was designed with an intended office for Mao Zedong, but was never fully used for that purpose. General Huang Yongsheng, who directed the project, is buried on the grounds.