The largest drain hole in the world.

One of the oldest reform schools in the United States, home to wayward boys such as Merle Haggard, now abandoned.

Outsider art or homage to aliens?

A working miniature city designed to teach kids about safety and presumably city planning.

Golden Gate Park's historic collection of plants.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

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

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

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

Olfactory delights in San Francisco's Botanical Gardens.

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

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

A psychedelic labyrinth on the San Francisco bay.

San Francisco's newly reopened hands-on science museum.

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.

Furniture tries to escape an abandoned building in San Francisco.

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

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

Scenic mount trashmore, Virginia Beach's most curious waterfront still has a couple of secrets.

A small Richmond island dotted with the remnants of hundreds of years of history.

An overgrown collection of miniature buildings still stand as evidence of one couple's obsession with The King.

This war hero's old shop remembers the fine line between medicine and quackery during the Revolutionary War.