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.

A library built during San Francisco's pioneer times is a student's retreat, bibliophile's sanctuary, and chess player's delight.

Faceless white figures loom over the city from the rooftop.

A monumental cross hides in the trees in Golden Gate Park.

Barely visible foundations remain where Stow Lake’s “observatory” once welcomed visitors.

Golden Gate Park's historic collection of plants.

California's most comprehensive horticultural library.

An artsy hidden staircase leads to breathtaking views of San Francisco.