The ruins of a world-renowned medieval hospital.

A long-forgotten Victorian swimming hole is still a fun spot for a dip.

An idyllic mineral hot springs facility with a more-than checkered past.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

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

Rich red almandine gemstones are waiting inside the volcanic rock strewn across this eastern Nevada hillside.

This lookout tower built in the 1930s is now an in-demand cabin with what might be the best view of the Seneca State Forest.

Get your cosplay on at Portland’s only Medieval fantasy-themed mead hall.

This edible park is open to any and all foragers.

Houses are tucked between, on, and underneath giant boulders.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Playable, historic pinball machines fill this Alameda museum.

The oldest hotel in the world has been operated by the same family for over 1,300 years, even catering to samurai.

One person's lost luggage is another person's treasure.

A failed utopian experiment for British expats in the American South is now a Victorian village frozen in time.

A humble garage, world-famous for being the epicenter of a technology revolution.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Spend the night in this formerly abandoned traditional Scottish village.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

Near this allegedly haunted pub, you can find strong spirits on the rocks.

The last occupied troglodyte dwellings in England weren't abandoned until the 1960s.

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

An architect transformed this abandoned cement factory into his castle-like workshop.