A top-secret bunker now turned museum, is an eerie look at what life would have looked like in the event of nuclear war.

Rusted structures stand like ghosts of Cyprus' 6,000-year-old copper industry.

This former Cyprus flight hub is now a crumbling, abandoned ghost complex.

Turkish adventurer antiques in the heart of the Grand Bazaar.

One of the largest wooden constructions in Europe was meant to be a casino, but soon became an orphanage.

Dubbed "Wistom" by locals, this abandoned factory is an urban explorer's dream.

Gliwice Radio Tower, likely the tallest wooden structure in the world.

What was once an underground Nazi city is now Europe's largest bat reserve.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

Most prolific publishing house in the 1600s open to the public.

A Cold War command center is hidden under an idyllic countryside.

One of the deepest indoor swimming pools in the world.

An abandoned Ecuadorian prison that once held ex-presidents and notorious con artists is now a carceral museum.

A nuclear power plant abandoned along with an international allegience.

A series of five defunct panopticon prisons in Cuba.

A grand imperial capital left to fall into magnificent ruin.

Now abandoned, the world's first torpedo factory is crumbling into the sea.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

At night, bats patrol this magnificent 18th-century space in search of book-eating pests.

Built to ward off Napoleon's army, this city-sized abandoned Russian fort is now perfect for urban exploration.

Moscow's imposing monument to the Space Age.

Museum celebrating the achievements of the Soviet space program.

Gargantuan home of Russian science.