The largest manmade caves in Europe now function as a motorbike club's headquarters.

This amazing mountain temple is topped by one of the tallest sitting Buddha statues in the world.

The remains of a magnificent medieval fortress that was the capital of a vast empire.

A desert that evokes the surreal.

On the outskirts of a desert trading village high on the Andean plain, steel giants have been destroyed by salt winds.

Bohol's mysterious brown hills.

Two monstrous faces loom over a village in Czechia.

Folklore says this medieval fortress was plopped atop a portal to hell to trap the demons below.

The largest geyser field in the southern hemisphere is a spectacular sight.

This hulking behemoth is actually five interconnected towers built in the 1960s.

It's hard to believe the dizzying patterns covering this abandoned mine are completely natural.

Left by the Devil, an ancient quarry or just plain old erosion, this enigmatic rock pillar rises 28 feet from the hillside.

Nestled in a peaceful valley, this Armenian monastery may have been saved from Mongols thanks to the eyes of God.

The most visited pilgrimage site in Armenia once held a saint in a pit for 13 years.

This Armenian monastery was carved out of cliffs and named after the spear used to stab Jesus.

A geological oddity topped with a 2,000-year-old pagan temple.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

This series of Armenian caves held the oldest brain, shoe, and winery in the world.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

Unlike many reclaimed, abandoned mines, this Canadian cave system is still just a dangerous maze.

An industrial site turned into Hungary's most cherished natural wonder.

This 12,000 year old Iranian cave village has been continuously inhabited for over 3,000 years.

At 705 feet high, Brazil's "House of Stone" is the largest cave mouth in the world.

A cave 150 feet beneath Kansas City is the perfect climate for growing 10,000 delicate orchids.