A two-inch thick solid brass rod that extends an astounding one kilometer straight into the earth.

Venue for strange sideshow displays and musical acts.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

This 600-year-old home seems to defy physics.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

No need to strap in for a "ride" on this walkable roller coaster.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

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

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

2300-year-old Roman road connecting the empire.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

The most visited, and possibly most controversial, museum in Germany.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The fairy tale castle of the "fairy-tale king."

World's largest collection of serial killer artwork and other macabre exhibits.

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