This 6th-century church honors St. Tudno, the patron saint of Llandudno.

An eerie, derelict amusement park in Berlin.

In the woods of New Jersey lie the ruins of a munitions village abandoned after World War I and the remnants of a 1920s wooden racetrack.

Perhaps the most spectacular grotto along the Algarve coastline.

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

For six months of the year, three giant mirrors direct a pool of sunshine onto this otherwise occluded town.

Once the site of the Hawaiian monarchy, this building was originally designed as a palace.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

A huge musical instrument played by the ocean.

Where America's first doomsday cult awaited the end of the world.

One man's ambition created this psychedelic log home.

This abandoned bridge to nowhere stands secluded in the woods of a Cleveland suburb.

This medieval "painted village" is famous for its geometric facades.

The "3rd largest" city in California is an empty mirage of suburbia in the middle of nowhere.

This unassuming Massachusetts residence was built with a trap door to hide escapees on the Underground Railroad.

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

A New Hampshire grave with a grudge.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.