A wealth of seafaring history displayed on the California coast.

Home to the "Circus" trees created by Axel Erlandson.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

Here, Father Agapius Honcharenko established his homestead, becoming the first nationally conscious Ukrainian to settle in the United States.

This bridge was constructed from the rubble of the infamous Bastille.

The oldest Naval chapel in the United States is home to an incredible collection of Tiffany stained-glass windows.

The last used bookstore in Downtown San Francisco is one of the smallest bookstores just about anywhere.

Enormous crabs, bioluminescent jellies, and other amazing creatures from the ocean’s depths—some of which are in an aquarium for the first time ever.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

This colorful boulder serves as a canvas for political statements and artistic expression.

For nearly 50 years, this San Francisco nonprofit has been serving as a mix of recycling center and art school.

Overflowing with shipping containers, this location has been transformed into a massive workspace for artists.

A 140-year-old castle with underground caves hidden in San Francisco.

Radioactivity still cause for concern at this urban explorer's paradise.

A library and museum dedicated to typography.

The model behind the iconic 3D test model.

From the Difference Engine to the Cray-1, all under one roof.

A gathering of green robots at the Googleplex.

The legendary statue-hating superintendent of Golden Gate Park is honored with... a statue.

Art in the form of a winding, man made crack in stone.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

A hidden subterranean installation offers a view of the sky.

Roadside Americana, fairy tale characters, and Austin quirkiness come together at this magical course in the heart of Texas' capital city.

This massive oak tree has ties to the first native tribes of the region and the founders of Texas.