Alien rock formations grown from the sands of an Australian national park.

This gracefully curving formation looks like a massive wave that was suddenly turned to stone.

Living fossils in this remote Australian bay provide a glimpse of what Earth may have looked like 3.5 billion years ago.

The world's second largest single-dish radio telescope, once used to contact E.T.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

Gothic tower mentioned in Thomas Hardy poem "The Channel Firing."

This hill and tower are steeped in legend, from King Arthur to the Holy Grail.

The oldest residential street in Europe also features an optical illusion.

The Bristol Camera Obscura housed in an ancient windmill.

A historic, reportedly haunted pub that provided inspiration for several famous adventure novels.

England's steepest street has such a drastic incline that locals tie their parked cars to lampposts when it gets icy.

Walk in the footsteps of the gods and straddle two tectonic plates.

This massive redwood tree has a hole in the base big enough to drive through.

A fascinating insight into daily life in the Eastern Bloc.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

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

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

One of Canada's most incredible rare book collections holds hundreds of thousands of gorgeous tomes that the general public can touch.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.