It is now called the Museum of Black Sea Forces. Before that, it was a top-secret submarine base. Until 1995, when it was abandoned.

The facility was born of the Cold War: following the US atomic bombing of Japan in 1945, Moscow feared the USSR could be the next target.

The Soviet Union began building underground bunkers for key installations, capable of surviving a nuclear attack.

The submarine dock in Balaklava – or the GTS-825 facility – was one of the first of its kind.

”Construction started in the mid-1950s by a special designated unit,” said Vladimir Mironov, a Balaklava Museum guide. “This mountain above us was very difficult to carve through and they had to set explosives inside in order to build these halls.”

Repairing small and medium-sized submarines was the facility’s priority. But in the event of an attack on the Soviet Union, the base in Balaklava could have been easily transformed into a platform for a retaliation strike.

”In case of a nuclear threat, the base could house up to nine submarines,” Mironov told RT. “It also had a military unit and a bunker, to where up to 3,000 people could have been evacuated. Apart from that, a special wing of the base was designed to create weaponry for submarines, including the most powerful ones.”

Now the base is almost empty, as most of its equipment was looted in the 1990s after it was deserted. But a small display suggests that the facility was once brimful with weaponry – and explains why it was so completely hidden.

The heart of the exhibition now, just several decades ago was a workshop where submarine torpedoes were repaired and assembled – including more than a megaton worth of nuclear weapons.

After presidents Medvedev and Yanukovich signed an agreement earlier this summer to prolong the Russian Black Sea Fleet’s stay in the Crimea until 2042, media speculation began about resurrecting the Balaklava facility.

Newspapers suggested that Moscow would invest in the base – and use it again to repair the Black Sea Fleet’s submarines. Kiev denied such claims, and the Balaklava Museum’s director Aleksandr Politov knows why.

”The facility was designed for small and medium submarines,” Politov told RT. “And it was built without any perspective into the future. From the 1970’s the Soviet Union started producing larger submarines which are in use nowadays. They are much bigger that those used in the 60’s and simply would not fit in the facility’s canal.”

Since opening in 2001, the Balaklava museum has been visited by tens of thousands, keen to learn some of the secrets of Soviet history. Those in charge of the exhibition say it serves as a lasting reminder of the times when the world stood at the brink of global confrontation.