This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A bizarre roadside attraction and the first instance of miniature golf in the world.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A fitting attraction for the corn capital of the world.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Medicinal spa created with the discharge from a geothermal energy plant.

The world's longest known cave system.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A bizarre house filled with an astounding array of collections.

Hear the quietest sound from across the dome.

See massive fossils that are over 200 million years old in northeastern Arizona.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

A beautiful geyser under environmental threat.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

The site of the climactic scene from the classic horror film is now a historic landmark.

The first declared National Monument in the United States.

Home to items never before seen by the public.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

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

A collection of 20th-century automata, penny arcade games, and musical contraptions.