The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

Located more than 600 feet beneath sea level, this tunnel boasts the world's first undersea roundabout.

In the foothills of the lesser Caucasus, a centuries-old fortress still stands.

The second-longest continuous wall on the planet protects a hidden secret in the deserts of India.

This temple contains what might be the world's oldest optical illusion.

The ruins of a resort and casino sit on the banks of this blue hole spring that pumps 70,000 gallons of warm, clear water every minute.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

Far from the shore, this sandy victim of the Skeleton Coast looks like it was plopped in the middle of the desert.

For this chef, an active volcano is his oven.

An ice field known for harboring an infamous Martian meteorite turned out to contain the oldest air on Earth.

Rock-cut cave complex filled with ancient Buddhist artwork.

See the rare bloom of the "Queen of the Night" cactus at one of the world's largest succulent collections.