One of the world’s largest and deepest freshwater springs, where mastodons once roamed.

A humid oasis combines recreation with exploration in a unique underwater cavern.

Welcome to old Florida, where a 1940s mermaid show is still enchanting visitors.

An abandoned underground bunker not far from downtown New Orleans.

This former POW camp was transformed into a Cold War missile installation.

A small car graveyard sits in the shadow of the famous Cadillac Ranch.

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

This outdoor observatory offers stellar views and a scale model of our solar system.

This huge dam across the Colorado River caused an armed standoff between two U.S. states.

Stepping away from the glitz of mobsters and casinos to learn about the other history of Vegas.

A massive hydrovolcanic explosion left a half-mile wide crater in Death Valley.

"Only the devil could play golf here."

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

Where NASA's satellites and rovers phone home.

Where decommissioned airplanes and helicopters go to become part of Hollywood.

A picture-perfect town, perfect for blowing up.

A mining town once rife with murderous disputes over its copious treasures now creates income as a popular spot for photo shoots.

Experience a charming 1930's version of "infotainment."

The lost ruins of the forgotten ferry lie hidden beneath the silt.

An urban laboratory.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

A partial tunnel blasted into a steep ridge is all that remains of a failed railway across Arizona.

Seller of surplus nuclear research materials.