Two hundred tons of pioneer artifacts were painstakingly recovered from a shipwreck at the bottom of the Missouri River.

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

The chiseled jaw of this forgotten American hero still stands tall in a small Indiana town.

The world's largest anatomically accurate brain sculpture.

Ornate limestone building now filled with geologic specimens, and more.

Curious cave that stays a cool 56 degrees all year long.

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

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

An emerald-green grotto just a short trip from Austin.

A place to eat for on-the-run agents and espionage enthusiasts.

Less a museum than a bizarre fantasy world created by artists and engineers.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

When ecosystems collide in the arid Southwest.

Community bookshelf of 25-foot-tall book spines.

The history of the treatment of mental illness, illustrated in all its gory detail, and housed in an asylum.

A unique geological area spiked with wind-carved rocks that resemble teepees.