Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

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

A huge musical instrument played by the ocean.

This teeny-tiny park built by a San Francisco man in 1962 is mostly stairs.

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

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

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

A modest reminder of treacherous waters at the Golden Gate.

Shoot for par over the bodies of the dead on this cemetery-cum-golf course.

Inside an old airplane hangar, friends and strangers alike play on a massive trampoline.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

Internationally-recognized arts center housed in a century-old former military barracks.

Concrete strongholds stand guard over the Golden Gate.

A living time capsule of the 1960s Richardson Bay water-front.

A working model of the entire San Francisco Bay and much of the Sacramento River Delta, complete with regular tides that change every 14 minutes.