The first fresco Diego Rivera painted in the United States can be found in the former San Francisco Stock Exchange.

Golden Gate Park's historic collection of plants.

Visible below the waves are memorials to the city's Gold Rush dead.

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

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

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

Olfactory delights in San Francisco's Botanical Gardens.

Its buzzing collection honors vibrator history.

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.

The story behind the mysterious symbol painted in front of the historic university's famous Rotunda.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

The ruins of this Thomas-Jefferson-designed mansion have been left to crumble since the Christmas Day they burnt down.

This secluded ruin was once a home for exotic plants.

A retired tobacco farmer's pet project turned into a sturdy miniature city.

An ancient neolithic tomb that only sees the sun twice a year.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

San Francisco's oldest surviving monument and meeting place for 1906 survivors.

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.

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

A jaw-dropping "megalibrary" that turns book-browsing into a geometric adventure.

Frida Kahlo's childhood home, now a museum of her life and works.

A museum in the former home of Marxist revolutionary Leon Trotsky.