In the early ’90s, nearly 100,000 people lived in a city that couldn’t be found on any map. It had no name, just a code: 404.

404 City is located on the sandy plains of Gansu province in China’s northwest, some 100 kilometers to the west of Jiayuguan City. Its name comes from 404 Co. Ltd., a company under the China National Nuclear Corporation. When the city was built in 1958, it served one purpose only: to host a nuclear bomb.

The country’s best nuclear scientists and experts were transferred to 404 — China’s first nuclear military base — along with mechanics, doctors, and other supporting staff. Six years later, in 1964, China recorded its first successful nuclear bomb detonation in the Gobi Desert in neighboring Xinjiang Uyghur Autonomous Region.

The city has an area of 4 square kilometers, with its own municipal government, police department, television station — even its own courthouse and prison. In fact, 404 is bigger than it looks, with a complete underground defense system in case of nuclear war.

Due to large-scale cave-ins, most people living in 404 were relocated to Jiayuguan in 2006. Now, only some 1,000 residents remain. Countless identical housing blocks stand empty, their doors sealed shut with walls of brick. The city park, once a nucleus of after-work entertainment, is deserted.

“The first generation of 404’s residents was also its builders. They are the best of every walk of life, chosen by the government from across the country to work together for China’s first atomic bomb, an important weapon for a country desperate to ensure its security from the United States and the former Soviet Union,” Li wrote.

It’s reported that only a smattering of 404 residents remain, with many people relocating to the western Gansu city of Jiayuguan.

Li’s account appears to back this up, with the ‘third generation of 404’ man stating that only elderly people remain in the city: “Only some old people live in that town, and they have decided to die there. I am afraid my hometown will disappear forever together with its last senior residents.”