Across Ring Mountain is a vast collection of Native American petroglyphs unique to the region.

The largest drain hole in the world.

Centuries of biking history are nestled in the shadow of the birthplace of contemporary mountain biking.

Of all the origin stories for weed's secret code, this one likely has the goods.

This whimsical seashell-shaped place of worship was designed to blend into its surroundings.

One of only five observatories in the world built to measure the Earth's wobble.

One of the largest Buddhist communities in the West sits on the site of an old hospital.

A sculpture dedicated to Napa Valley's oldest mineral water company.

Nursery with extensive collection of flesh-eating plants operated by the author of "The Savage Garden."

A poignant memorial to a young boy whose death spurred a dramatic increase in organ donations in Italy—dubbed the "Nicholas Effect."

Celebrating the transformation of trash into objects of beauty.

An optical illusion found amid a logged redwood forest.

This massive redwood tree has a hole in the base big enough to drive through.

Experience Larry Spring's self-taught "common sense" laws of physics.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

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

The haunting ruins of Jack London's dream house.

Once the largest winery in the world, this castle-like building now sits abandoned on the San Pablo/San Francisco Bay shore.

The oldest Naval cemetery on the West Coast.

The former Naval shipyard is open for exploring - mostly.

The timepiece that exonerated a labor radical accused of a parade bombing that killed ten people.

The perfect spot for a picnic, right next to a giant ballistic missile.

An abandoned Cold War missile radar site.

An "anarchical" no man's land, complete with garbage sculptures and a hobo-run "Landfillian Library."