The hippo that stands on this university campus was once a drunken flea market purchase.

The narrowest street in the world is in danger of closing up entirely.

The great Danube river starts here.

A Black Forest cuckoo clock theme park features one timepiece big enough to walk inside.

An ancient monastery, a locked room, and a mysterious book heist.

The woman who helped save 15th-century France was born in this humble home.

This building’s ghostly exterior reflects its former lives as a prison, school, and funeral home.

One of the last mosaic tile facades found in the city.

The final residence of an educator, civil rights leader, and presidential advisor was also the first headquarters of the National Council of Negro Women.

This rowhouse doubles as one of the most photographed spots in the nation's capital.

Two elaborately decorated "catacomb saints" are displayed on either side of the altar in a small church in Germany.

This Rococo church is known as the most beautiful village church in the world, and does not disappoint.

A striking 12th-century-style castle built on the edge of a cliff.

A brass and marble scale model of the solar system embedded in the concrete.

Also known as the Founding Church of Scientology.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.

This magenta statue commemorates the legendary marriage between a mermaid and the city's founder.

The official motto of Luxembourg reminds passersby of the Luxembourgish commitment to their national identity and sovereignty.

Statues of a fire-breather, a clown, and a whole performing troupe celebrate Luxembourg's creative side.

Some believe that the artist behind this whimsical statue inserted his own likeness as a way to discreetly flip the bird.

This old wooden funicular railway leads to a cemetery in the forest.

This former quarry is now a picturesque gorge that hides a sunken lake.

A farm turned upside down.