A popular swimming hole that hides one of America's most deadly diving spots.

This Texas windmill field celebrates the power and majesty of the very winds that blow.

An emerald-green grotto just a short trip from Austin.

This beautiful grotto is one of those places where you can't believe you're just outside Austin.

Civil War dumping ground for the bodies of terrorized Union sympathizers.

This sacred cavern, 400 feet deep, is home to millions of bats and an ancient burial ground.

An immense cave that has served as an outlaw's treasure trove, an underground dance hall, a nuclear fallout shelter, and much more.

A Texas cave network is home to some of the world's most spectacular-looking and bizarrely named mineral formations.

Hike the ruins of a zoo that was shut down by an unsolved murder.

A tribute to the little-known group of women who were the first ever to fly aircraft in the U.S. military.

A hidden sculpture garden tucked within the middle of Brighton.

A private selection of curiosities, carefully curated by a young Brighton local.

One fisherman has used his love of pebbles and shore to create a crazy garden of rocky art.

This concept building is the UK's first attempt at making a permanent structure of nothing but trash.

The natural history museum displaying the British bird collections and dioramas of Edward Booth, free of charge.

This tiny alleyway is now a shrine to a subculture riot between the mods and rockers.

A mysterious Neolithic tomb is perched along the edge of a modern golf course.

Once an ancient sea, this landscape of rocky ravines is filled with the fossils of ancient marine life.

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

Catacombs turned marketplace.

This South London cemetery holds the remains of more than 15,000 people.