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

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

Tiki luxury on Nob Hill.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

An essential stop before plundering, BYO Cutlass.

A modern mechanical planetary system, part of a 10,000 year clock.

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

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

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

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

The romance of early commercial flight still fills this Art Deco destination.

Elevated freight railway turned wildly successful urban park.

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

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

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

World's first "penitentiary," meant to be humane, drove men insane.

A huge musical instrument played by the ocean.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A historical convent known for taking in bad luck babies left on its doorstep is now an upscale shopping center.

The largest pool at its elevation sits on top of one of the most expensive resorts in the world.