Built by the inventor of the radio, this abandoned hotel has housed early radio employees, military men, and a dangerous cult.

Hidden beneath a lake for decades, this brutalist mine has now emerged from beneath the receding waters.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

The glowing blue Nymphaeum of Emperor Tiberius.

Two World War II aircraft lie within the jungle around this abandoned runway.

This lonely cast-iron structure is the only wave-washed lighthouse of its kind left in all of Britain.

This former military airfield's claim to fame came from a lucky accident during the Second World War.

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

This mountain tram provides stunning views while hanging from a single, steel thread.

A medieval castle in the middle of rural Texas.

These boots are made for selfies.

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

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

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

A modernist landscape of water and sci-fi concrete.

The largest pool at its elevation sits on top of one of the most expensive resorts in the world.

The Grand Canyon of Texas.

An abandoned quicksilver mining town surrounded by the Big Bend parks.

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

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

Five mile wide circular ring of rock in the Russian Far East is a curious geological oddity.

Some of the world's only freshwater seals live in one very special lake in Russia.

The convergence of two currents makes this a surprisingly pleasant getaway in the Arctic Circle.