A house built from trash known as the poor man's Hearst Castle.

The fossilized remains of ancient California redwoods.

The haunting ruins of Jack London's dream house.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

A popular tourist cave with a dark past.

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

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.

An extensive collection of ancient Egyptian artifacts and mummies.

This unlicensed collection of fast-food memorabilia sits on the site of the first ever McDonald's restaurant.

The unbelievably opulent home built for an infamous newspaperman.

The oldest burial ground in the city, final resting place of city founders, Ohlone natives and murderers alike.

One of the ghostly stops along Route 66.

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

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

Quite simply the largest tree in the world (by volume).

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

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

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

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.

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.