The 816 Project, situated in Baitao subdistrict, Chongqing, was China”s second nuclear material industrial base. It was approved for construction in 1966.
More than 60,000 people worked on the top-secret underground nuclear facility over an 18-year period, with a total investment of 746 million yuan ($110.6 million). It is now the world’s largest declassified artificial cave.
After construction was halted, the site was declassified in 2002 and opened to the public as a tourist attraction in 2010. This enigmatic and awe-inspiring site features 18 large caverns, along with over 130 roads, pilot tunnels, branch tunnels, passages, and shafts.
Visitors can now explore areas like the reactor bottom cavity, reactor hall, diversion tunnels, thermal circuit building, and instrument room.
The 816 Project has been included in the list of Chinese 20th-century architectural heritage and has been designated as a national 4A-level tourist attraction. It also serves as a national industrial tourism demonstration base and a patriotic education center, attracting visitors from around the globe.