Secret nuclear bomb-proof steel door at Beijing subway station

During the Cold War, Beijing's subway stations served as bomb shelters to protect the city's residents from nuclear attacks, according toPopular Mechanics.

Many train stations are equipped with heavy steel doors designed to provide safe shelter from a large explosion. These doors are cleverly camouflaged within the station walls, making it impossible for people to detect their presence or the government's nuclear war preparations.

Photo goes viral on Chinese social mediaA recent photo shows a thick steel plate extending from the floor to the ceiling between the wall of Chongwenmen Station in Beijing and another steel plate lying on the station floor.

According to experts, these steel panels that do not fit in with the surrounding architecture are actually where the bomb-proof doors are hidden. In the event of a nuclear attack, station staff will remove the steel panels from the floor, revealing a tunnel through which the doors can move. When the doors close, people sheltering inside will be protected from the heat, pressure, and radiation of the nuclear explosion.

Since 2007, with the support of the Chinese Rocket Force, the entire Beijing subway system has been renovated with two layers of emergency protection above the station ceiling and below ground. The door installed underground weighs 7 tons. Each station has a three-hour backup oxygen supply system.

In 2012, Chinese media reported that Beijing's subway system could protect residents from typhoons, nuclear attacks, and even toxic gases.

However, experts say the effectiveness of this measure has yet to be proven. If Beijing were hit by a nuclear attack, survivors hiding in the subway station would die later because after three hours they would have to open the door to get oxygen and would certainly be exposed to radiation.