A self-taught astronomer fell in love with the stars and built his own observatory in Colombia.

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.

This incredibly diverse research station is one of the largest tropical botanical gardens in the world.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

The world's largest floating loon bobs in the lake to kick off an annual festival.

A wall within the institution displays the names of 13,000 Jews who took refuge in the city during World War II.

The ornate miniature mansions were built for Istanbul's feathered residents.

A futuristic hovertrain is parked unceremoniously alongside a nondescript road.

The unique circular corral belonging to the “Cattle King” of Oregon.

An eclectic collection of artifacts from the Wild West is preserved in a remote fictional pioneer town.

The Cold War-era "underground Pentagon" is a sprawling subterranean hideaway for the Defense Department.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

Visitors are welcome to enter this lush Key West sanctuary to entertain its plethora of rescued parrots.

Where pardoned turkeys once spent their all-too-brief final days.

The Netherlands is home to a bridge printed out of reinforced concrete.

Find out what it sounds like when doves cry at Prince's recording studio estate turned museum.

The largest open-air contemporary art center in Latin America is a unique experience in the Atlantic Forest.

This romantic, decaying 13th-century ruin on the edge of Sherwood Forest is reputedly one of England's most haunted places.

The remains of a 1st-century aristocratic Roman town house featuring beautiful well-preserved mosaics.

One of the last doorless, continuously moving elevators still in use in the U.K.

This Soviet-era "closed town" was a top secret uranium producer often left off of maps.

Every hour the doors open to reenact the legend of the heroic mayor who saved his town by drinking a gallon of wine.

An impressive century-old, to-scale topographical map of Guatemala.

Home to a full cast of the largest woolly mammoth ever recovered in North America.