Gargantuan home of Russian science.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

This 15th-century cave complex is one of the very few monasteries to stay open throughout World War II and the Soviet regime.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

This newly renovated Soviet-era outdoor exhibition center is bigger than the principality of Monaco.

Hidden in a metro shop under a shopping mall, this small museum tells the story of one of the world's largest urban transit systems.

World's largest bell sits on the grounds of the Kremlin in Moscow.

Former headquarters of the KGB.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Dr. Strangelove-esque tours reveal the inside a bunker once reserved for Stalin himself.

Moscow's other, lesser known kremlin is a fairytale-like cultural complex modeled after Old Russia.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

The world's most active stratovolcano is almost always erupting.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

Too much gossip or just missing curfew could land you in here for a couple of days.

Thousands of slain Soviet soldiers are buried within the shadow of this enormous obelisk.

An unusual cave filled with rare alien-looking aragonite formations.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

A perfectly preserved hill village where the buildings are painted like white lace.

A unique hotel for the artistic soul.

The blood-soaked ruins of the castle where the murderous Blood Countess was walled in alive.

The ruins of an Estonian prison are drowning in the quarry lake where the convicts were once forced to work.