Erotic art covers the walls of the largest ancient pleasure palace.

The quintessential Japanese rock garden has existed for more than 500 years.

Replicas of Apollo's leonine stone guard cats still line a sacred row in Greece.

The first U.S. town to secede from the Union, only to vote themselves right back in.

Forgotten and then destroyed by fire, this was once one of the largest saltwater swimming pools in the world.

Architectural monsters are devouring this palace's every door and window.

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

The modern birthplace of Irish freedom.

An extraordinary "City of Caves" carved from solid stone.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

This series of Armenian caves held the oldest brain, shoe, and winery in the world.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

A geological oddity topped with a 2,000-year-old pagan temple.

This Armenian monastery was carved out of cliffs and named after the spear used to stab Jesus.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

Unusual building appears to be haphazardly built from randomly piled bricks.

Ancient rock-hewn town that witnessed key events of Georgian history.

Underground monastery and fortress.

A museum glorifying the life of Stalin, located in the city of his birth.

Mysterious hillside with a continuously burning natural fire.

A shrine of fire worship built on top of a natural flame.

The oldest burial ground in the city, final resting place of city founders, Ohlone natives and murderers alike.

Dentist's hated concrete colossi are now beloved icons of the community.