Thirteen trees representing the original thirteen colonies were planted with soil from historic Revolutionary battlefields.

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

A hidden subterranean installation offers a view of the sky.

Its buzzing collection honors vibrator history.

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

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

A huge musical instrument played by the ocean.

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

These six walrus head statues harken back to a time when this area wasn't far from the oceanfront.

A pair of mutilated bronze octopuses slump at the base of the monument honoring California's admission to the U.S.

Although it also features red, orange, and variegated cliffs of Navajo Sandstone, this state park is often overshadowed by its more famous neighbor.

This former New Jersey bus now exists as a public art exhibit.

Inspiration struck on this seat outside the Griffith Park merry-go-round.

A facility built in 1992 for an underground nuclear test remains in place today.

This former mining railroad is one of the best-preserved short lines in North America.

Built for an exposition in 1915, these horticultural displays have stood the test of time.

The shop's owner has spent decades in the desert wearing nothing but a strategically placed sock.

The stone-covered graves lie within the ruins of an Old West ghost town.

Take a dip in the world's largest mineral hot springs pool.

This nondescript tunnel has been featured in a number of iconic movies, from “Roger Rabbit” to “Back to the Future.”

This rest area is also home to a remarkable petroglyph site.

The precious-metals strikes dating back to the 1860s are now mostly inactive, but this area has become the United States' only domestic source of lithium.

The self-proclaimed gateway to the Extraterrestrial Highway.

The so-called "Father of Las Vegas" had the city's first telephone installed in his office in 1907.