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

Olfactory delights in San Francisco's Botanical Gardens.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

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

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

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

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

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

A psychedelic labyrinth on the San Francisco bay.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

A huge musical instrument played by the ocean.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

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

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

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

A strange house built only at night, with rumored mystic inspiration.

Finale of "William Tell Overture" can be heard as drivers pass over grooves in the road.

This golf ball–shaped former desert real estate office now houses a UFO museum.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

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

Ancient pueblos built into the base of a natural canyon wall.

The collection of signage remembers the midcentury pushback against the new neon light.

At just six feet two inches deep, it is said by Guiness and Ripley to be the world’s narrowest freestanding office building.