The U.S. Navy's last diesel-electric submarine rests half-submerged in the middle of Portland.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

The only parking meter in the entire town, it is surrounded by 100 free spaces.

A huge collection of rocks, gems, and crystals.

The unedited photograph called "Bliss" has graced the screens of over a billion computers.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

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

This residential door allows San Francisco muggles a glimpse at the wizarding world.

A psychedelic labyrinth on the San Francisco bay.

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

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

A hidden gem, named after a San Franciscan icon, offers spectacular views of the Pacific Ocean.

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

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

Home to one of the world’s largest collections of model yachts.

San Francisco's first World's Fair, dedicated to the wonders of California.

A hidden subterranean installation offers a view of the sky.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

Art in the form of a winding, man made crack in stone.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

A garden oasis filled with flowers mentioned in the works of William Shakespeare.

The taxidermied remains of the "last wild grizzly bear in California" and of the symbol of the state of California.

A century and a half of research in the sciences and natural history, still going strong.

Over 315,000 preserved amphibians and reptiles in jars.