One of the world’s largest collections of petroglyphs records 2,000 years of human activity.

A 19th-century cabin built into a hollowed-out Sequoia tree.

Rusty pieces of metal jutting out of a breakwater are all that's visible of the 12,500-ton ocean liner that capsized just off the beach.

A Roman-inspired temple once controlled half of San Francisco's waters.

Hidden in the Santa Ynez Mountains off Highway 154, this tiny restaurant once served as a stagecoach stop.

A 300-ship graveyard, with a few still visible at low tide.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

A winding path built in secret on the edge of the continent.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

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

This hidden fire lookout offers spectacular views of Sequoia National Park.

The largest wildlife crossing in Utah allows local fauna to safely traverse the six-lane Interstate 80 at Parleys Canyon.

Few things look more out of place than the electric blue ponds in the reddish-brown desert of Utah.

The fifth-longest natural arch in the world, and the longest outside China.

Despite its name, this route in southern Utah offers a heavenly day trip.

Silver in the hills led to the speedy creation of this boom town and a lack of it saw the town abandoned nearly as quickly.

Despite being one of the most photographed vistas in the Rockies these twin peaks are rightfully known as the "Deadly Bells."

The world’s largest concentrated solar plant generates as many problems as megawatts.

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

A B-17 bomber stands as a memorial to the residents of Tulare County who served in World War II.

An abandoned 1920s-era stretch of cabins now overshadowed by the 66 Motel.

A pair of giant roadside arrows are all that remains of a former Route 66 trading post.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.