This massive underground salt mine now holds a sci-fi theme park in its depths.

Rock carving created 1,300 years ago 75 feet off the ground.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

Romania's triumphal arch looks out over Bucharest.

This once-derelict building is now one of the most beautiful bookstores in the world.

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

Gigantic Romanian salt mines used to heal respiratory conditions.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

This attraction was abandoned after the Chernobyl disaster.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

The dining hall that nourishes workers in Chernobyl's Exclusion Zone is also open to visitors.

This derelict superstructure was a very important warning system for the Soviet military.

340-foot statue built to honour the Heroes of the Soviet Union.

This 1000 year old relic-filled cave monastery and UNESCO World Heritage Site also hosts an amazing micro-miniature museum.

The haunting complex honors the millions of Ukrainians who died in the forced famine under Soviet rule.

The deepest metro station in the world.

An Art Nouveau building covered in animal gargoyles and grotesques.

One of the world's tallest statues is also one of its most hated.

Dozens of padlock-trees along the Moscow River.

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

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

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

A city block packed with whimsical sculptures that seem to be plucked from a tiled fantasy world.