Hidden behind a nondescript garage door of a remote house at the end of a lonely road east of the town of Konjic in what is now Bosnia, is an abandoned relic of the Cold War.

Behind three heavy metal doors more than a metre thick, a tunnel leads to a secret bunker located 900ft (270m) underground.

Communist Yugoslavia's strongman Josip Broz Tito ordered the building of the bunker in 1953 to safeguard the country's ruling class in case of a nuclear attack.

The attack never came – and nor did Tito. Construction was finally completed in 1979 – a year before the dictator's death.

He never got to see the U-shaped complex dug into the mountain with 100 bedrooms and the "presidential bloc" containing private quarters built just for him with a king-size bed and an en-suite bathroom.

The complex, spanning 6,500 square metres, was designed to allow 350 people to live and work for six months without ever coming up for air. It had its own generators, water supply and air-conditioning system.

The existence of this atomic shelter that could withstand a nuclear attack strength of 20 kilotons was known only to four generals and the handful of soldiers guarding it.

The bunker is now open to the public as a museum and a space for modern art exhibitions.