The remains of this hell for leather wild west town can still be found in the Arizona desert.

A stealthy Apache hideaway that became the haunting site of a mass grave.

A 90-foot-tall psychedelic "tree" on the side of the highway has baffled passersby for decades.

Visitors to this library are in for a real-world education in modernist architecture.

This concert pavilion on the shore of the Great Salt Lake has been destroyed by fire, water, and disinterest but keeps coming back.

A sculpture for the sun and stars, created by Nancy Holt.

A replica that won't float away.

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

A Mars simulation in the southern Utah desert.

The glowing blue Nymphaeum of Emperor Tiberius.

The Emperor Tiberius' palace of debauchery.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

A local landmark with generations of spraypainted messages, and more being added each day.

Pensacola's UFO home has withstood many hurricanes—just as the experimental 1960s design intended.

This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

A whimsical bridge adorned with decorative dragons.

This massive subterranean fissure is known as the "underground Grand Canyon."

An ancient Egyptian temple in the middle of Madrid, Spain.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

The oldest known university in the world is in Fez, Morocco.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

The other side is actually green.