This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.

This tower once served as a radar station during the Cold War.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

In Portugal, a secluded stretch of untouched natural beauty hides at the bottom of a steep hill.

Six times a day a train runs right through the middle of this Thai street market, sending vendors scrambling.

World's largest cave was only discovered in 1991, and now offers tours to the public.

Temple of a million beers.

A modern temple with an ancient philosophy.

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

Thirty creepy ghosts now inhabit this decaying 14th-century church.

Two monstrous faces loom over a village in Czechia.

Twice a day a speeding train passes only inches from the homes of this residential neighborhood.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

This quaint Spanish village agreed to be painted blue as a marketing stunt but found that they preferred it that way.

Picturesque intersection of witchcraft and ancient Christianity.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

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

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

This small chapel is built of human bones and decorated with a golden skeleton.

Founded as a refugee camp, now a popular tourist spot.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

Hundreds of hidden passageways weave through the old quarters of Lyon.

An enchanting monastery in the Spanish countryside appears lifted from a fantasy tale.