The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

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

Nine of the very few concrete ships ever made in the U.S. are beautifully decaying off a Virginia pier.

An eatery in a shallow river where diners can enjoy their meal mere feet from the base of an artificial waterfall.

A gigantic sculpture garden is packed with innovative oddities.

A once-thriving hotel in the Swiss Alps couldn't compete with climate change.

This family tattoo parlor has been inking religious pilgrims in the Middle East for 700 years.

In the foothills of the lesser Caucasus, a centuries-old fortress still stands.

An abandoned vacation home spent a decade taking on legends. It's now taking on water.

The longest navigable underground river in the United States is home to countless blind and albino animals.

The cell which saved the life of Ludger Sylbaris, "the man who lived through Doomsday."

A small part of Russia that does not touch any other part of Russia.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

A fire lookout atop a glacial pinnacle is reached by climbing three vertiginous flights of stairs.

The second-longest continuous wall on the planet protects a hidden secret in the deserts of India.

For millennia, explorers were obsessed with discovering the source of the Nile—is this small mountain stream really the answer?

Although it appears much older, this castle-like tower is actually a Georgian-era folly.

Chef Lawrence West serves up Indian tacos, wojapi, and other Lakota dishes at the brick-and-mortar incarnation of his popular food truck.

Accessible only by boat, this centuries-old island fort never saw troops or combat.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

This ruined fort and statue are a testament to the last king of Kaua‘i’s savvy diplomacy skills, which briefly brought Russians to Hawai‘i.

Where condemned pirates met their grisly end at the gallows on the River Thames.

The world's oldest soul food restaurant is also one of its best.

America's oldest Italian restaurant is a San Francisco institution.