Stalactites and stalagmites in a beautifully lit cave.

The titular "little arch" near this Italian resort is one of the most popular diving spots in the country.

This elaborate hole in the ground was built as a sacred site for an ancient civilization.

A striped 12th-century basilica sits in the countryside of Sardinia.

Mysterious tombstones thought to be remnants of Atlantis.

Windblown rock formations in an ancient Roman quarry.

This statue is dedicated to the animal cosmonauts that perished during space flight experiments.

How this choice of tombstone came to be is still a mystery.

This Latvian shot factory is still used twice a year to manufacture bullets the old-fashioned way.

Built to ward off Napoleon's army, this city-sized abandoned Russian fort is now perfect for urban exploration.

Fast food feels like fine dining at this award-winning modern Georgian building.

A gleaming white and undulating tower marks the border between Georgia and Turkey.

The first skyscraper to include a Ferris wheel built into the facade.

Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.

A literally moving statue of stacked metal giants just continually trying (and failing) to find love.

The cave holds a spectacular array of stalactites and stalagmites, including one shaped like a giant human heart.

The decaying remains of a once-luxurious Soviet spa town.

This neon lit Georgian cave claims to hold the boulder Prometheus was chained to.

These Stalin-era industrial 'death traps' hang lifeless above the city

Small church on top of a huge rock column.

This extensive collection of vintage Soviet cars is the only one of its kind in the Caucasus.

You'll find just about anything in this funky Tbilisi flea market.

The last standing example of an ancient district's teatime tradition.

When the Soviets destroyed the historic Armenian monastery they somehow left its bell tower intact.