This one-time health resort was used by aristocrats around the world.

This massive subterranean fissure is known as the "underground Grand Canyon."

A whimsical bridge adorned with decorative dragons.

The small cliffside monastery known as the Tiger's Nest is said to be the meditation site of an eighth-century Buddhist master.

This Himalayan airport provides one of the most difficult landings in the world.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Home of Philip Johnson, one of the 20th century's most influential architects.

100 massive sculptures in the Hudson River Valley.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

Books bound in human skin and H. P. Lovecraft's letters are among a few of the treasures this library has to offer.

A mysterious stone embedded at the base of a historic Boston building.