Natural catch-basin rocks covered in thousands of drawings spanning many millennia.

Abandoned railroad tunnel is home to a colony of three million Mexican free-tail bats.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

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

The top of a giant mesa, just outside of Amarillo, appears to float in the sky above.

Scale replica of China's ancient terracotta tomb warriors and Forbidden City are the side project of an eccentric millionaire.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

Moonbows over Kentucky.

One person's lost luggage is another person's treasure.

Famous for its bio-luminescent inhabitants, known as "Dismalites" .

The perfect place to take a family of giants for a beach vacation.

This sacred cavern, 400 feet deep, is home to millions of bats and an ancient burial ground.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

An enormous, inside-out glass globe built in 1935.

Gleaming self-built castle towers made from beer cans and inspired by "Vitamin Mary Jane."

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

One woman's UFO-themed campground, complete with self-built energy vortexes, UFO-themed weddings, and magic bushes.

A hand-built folk art installation covered with messages of God's love.

Giant Redwood-themed cafeteria operates under the golden rule, "Dine Free Unless Delighted."

A massive underwater sinkhole made famous by Jacques Cousteau.

Only known mainland rookery of the threatened Stellar sea lion.

Stalactites and stalagmites in a beautifully lit cave.

Underwater art project will double as a massive artificial coral reef to help regenerate the damaged ecosystem.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.