Deep below the thick ice of Greenland lies a labyrinth of tunnels that were once thought to be the safest place on Earth in case of a war.
First created during the Cold War, Project Iceworm saw the US plan to store hundreds of ballistic missiles in a system of tunnels dubbed ‘Camp Century’.
At the time, US military chiefs had hoped to launch a nuclear attack on the Soviet Union during the height of Cold War tensions if things escalated.
But less than a decade after it was built, the base was abandoned in 1967 after researchers realised the glacier was moving.
Now, the sprawling sub-zero tunnels have been brought back to attention in the stunning new images.
Alex Gardner, a cryospheric scientist at Nasa’s jet propulsion laboratory said: ‘We were looking for the bed of the ice and out pops Camp Century. We didn’t know what it was at first. In the new data, individual structures in the secret city are visible in a way that they’ve never been before.’
The underground three-kilometre network of tunnels played host to labs, shops, a cinema, a hospital, and accommodation for hundreds of soldiers.
But the icy Greenland site is not without its dangers – it continues to store nuclear waste.
Assuming the site would remain frozen in perpetuity, the US army removed the nuclear reactor installed on site but allowed waste – equivalent to the mass of 30 Airbus A320 airplanes – to be entombed under the snow.
But other sites around the world – without nuclear waste – could also serve as a safe haven in case of World War 3.
Wood Norton is a tunnel network running deep into the Worcestershire forest, originally bought by the BBC during World War 2 in case of a crisis in London.
Peters Mountain in Virginia, USA, serves as one of several secret centres also known as AT&T project offices, which are essential for the US government’s continuity planning.
Further north in the states, Raven Rock Mountain Complex in Pennsylvania is a base that could hold up to 1,400 people.
And Cheyenne Mountain Complex in El Paso County, Colorado, is an underground complex boasting five chambers of reservoirs for fuel and water – and in one section there’s even reportedly an underground lake.