These ruins of a pre-Columbian cliff village are among the most beautiful and well preserved in New Mexico.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

A museum dedicated to the alleged Roswell Incident.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

On the outskirts of a reborn ghost town, a decaying post office remembers the bad old days.

A spiritual vortex among the red rocks in Sedona.

A self-built castle made by a mysterious man.

New fungal and bacterial species call this deadly lake home.

An Idaho legend carved out a cave village with his own two hands.

Home to the deepest rift anywhere on Earth.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

'Cause the fence start shaking, the earth was quaking.

A classically inspired temple in Redwood City.

This concert pavilion on the shore of the Great Salt Lake has been destroyed by fire, water, and disinterest but keeps coming back.

Step into the cool deep past and unknown future of who begat who.

This granite monument at the site of an ill-conceived tourist attraction is built from the same stone as the Mormon Temple.

This crumbling Death Valley mining complex was known for its use of giant, 20-mule team wagons.

A geological mystery on Camelback Mountain.

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

A 90-foot-tall psychedelic "tree" on the side of the highway has baffled passersby for decades.

A towering tribute to decisiveness stands on the spot where Brigham Young and his followers decided that this must be the place.