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

This museum showcases the history and contributions of the U.S. Army to the medical industry, both on the battlefield and off.

A gorgeous garden oasis with winding paths, stone bridges, and a troubling history.

Craggy concrete faces are hidden in the walls of this artificial cave along the San Antonio River.

Seven flags adorn this Texas museum, one for each of the powers that have ruled the area.

Ruined pieces of stone and a swimming pool are all that remain of an amusement park swept away by a flood.

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

A one-of-a-kind collection of a unique medium.

A 140-year-old castle with underground caves hidden in San Francisco.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

A psychedelic labyrinth on the San Francisco bay.

Non-profit time travel mart sells goods you would need for a trip through the fourth dimension.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

A huge musical instrument played by the ocean.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

Medical and zoological curiosities for sale.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

Crypt mausoleum in cathedral's basement contains relics of third century Roman martyr, Saint Vibiana.

A hotel and restaurant serving as the mecca of kitsch.

A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.