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

A monument to the love people have for their pets.

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

Inside this museum, the history of the Walt Disney Family empire is on full display.

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

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

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

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

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

Prone to disastrous fires, the city of San Francisco has the Guardian, a fireboat gifted by residents, to watch over them from the bay.

At night, this glittering musical tunnel draws skaters and photographers.

One of the most elaborate displays of Jellyfish is on display at the aquarium.

The only standing town in the United States that early Chinese Americans built for themselves.

A fake block of cheese remembers a feat of dairy engineering from the Chicago World's Fair.

Yale University's home for rare works, including the mysterious Voynich Manuscript.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

This is the oldest Roman-made bridge in the city still existing in its original state.

This ancient market is often referred to as the oldest shopping mall in the world.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

2300-year-old Roman road connecting the empire.

The yawning maw of this pagan visage is said to bite off the hands of liars.