An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

Secret North Korean passage discovered below the world's most dangerous border.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

The only theatre in the world constructed specifically for sound movement.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Open-air museum with a large collection of Soviet-era statues.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

Historic slum of Tartu.

First point in the Struve Geodetic Arc, a 19th century undertaking to measure the Earth's size and shape.

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

Former headquarters of the KGB.

Berlin's old airport.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

This micro-nation may be some sort of prank, but its constitution sure seems official.

This attraction was abandoned after the Chornobyl disaster.

The "Prussian Versailles" that is as glorious today as when it was built.

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.

Moscow's imposing monument to the Space Age.

Museum celebrating the achievements of the Soviet space program.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

One of the largest ochre quarries in the world, hidden in a limestone landscape.