When Croatia became independent of Yugoslavia, the splintering governments left behind these concrete tunnels.

A wonderfully strange collection of 500+ stuffed frogs doing people things.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

A hands-off space for graffiti artists to hone and display their skills.

This former theme park in New York's Adirondack Mountains fell into ruin before being resurrected as a state-run campground

This imposing tower named after the mythical sword of King Arthur is considered the tallest freestanding climbing wall in the world.

For a century, the tallest building in Tasmania was a tower built to manufacture ammunition.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

White beach sands made of the remains of tiny, star shaped creatures.

This massive underground salt mine now holds a sci-fi theme park in its depths.

World's oldest and largest space launch facility, once a secret missile testing site.

The atmospheric road was never meant to be so creepy.

Stunning examples of Russia's 18th-century wooden architecture.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

The oldest hotel in the world has been operated by the same family for over 1,300 years, even catering to samurai.

Former military fort and site of untold horrors during WWII, this island may become the Adriatic's next luxury resort.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

Abstract dinosaur models in London.

Shakespeare, David Bowie, Dr. Who, the Saxons, Druids and Romans are all claimed to have all made their mark on these massive man made tunnels.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

This 16th-century monastery has been turned into a surrealist architecture compound.

The remains of Crystal Palace Great Exhibition of 1851.

England's oldest surviving hedge maze has been confusing visitors for over 300 years.