Modern design and unusual architecture make this mountaintop temple no ordinary Buddhist retreat.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

A modern-day Lascaux cave underneath Paris.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

Hiding the longest subterranean river known in the world.

A Japanese concept restaurant that feels like a party thrown by the monsters in your closet.

An inconspicuous footbridge beloved by San Diego locals.

Unparalleled stargazing, one of Colombia's best observatories, and a swimming pool can all be found in the middle of this ancient tropical forest.

A luxuriant botanical garden below sea level.

The streets of a sleepy Spanish town proudly exhibit some of the world's finest graffiti.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Deep in the Thar desert, a temple crawling with thousands of holy rats.

Mine your own precious stones.

A gargantuan crystal kingdom.

At this California chicken ranch, four bucks will get you 18 eggs and a chorus of dancing animatronic poultry.

A marvel of Byzantine engineering under the streets of Istanbul.

A legendary speakeasy bookstore returns from the brink.

A Spanish town built into the cliffs.

The world's only museum devoted to the wonders of fluorescence.

Non-profit time travel mart sells goods you would need for a trip through the fourth dimension.

An enormous, inside-out glass globe built in 1935.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.