The ruins of an 11th-century Norman castle with a rare, perfectly circular shape.

San Francisco's oldest operating hotel, with a Victorian atmosphere and a "haunted" fourth floor.

A walk down memory lane in the heart of one of San Francisco's most notorious neighborhoods.

Art from the latest counter-culture; kids who dye their hair blue and believe the future will be a post-apocalyptic water world.

With the touch of a button, you can read a randomly selected short story.

Tenacious mummies survived dental problems, eternal entombment, and more than their fair share of devastating fires.

Golden Gate Park's historic collection of plants.

The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

A collection of memorabilia from the Beat era in the back of a San Francisco bookstore.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

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

A historic hotel that made a cameo in Hitchcock's classic film has no intention of letting guests forget its fame.

A still functioning vaudeville carousel that has operated for over a century boasts a colorful menagerie and past.

A hidden subterranean installation offers a view of the sky.

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

Nestled in the heart of San Francisco’s bustling Financial District stands a unique homage to the Mayan and Beaux Arts.

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

The tea room that pushed the boundaries of adorable straight into...we can't find the words.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

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

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

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

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

Olfactory delights in San Francisco's Botanical Gardens.