An inconspicuous footbridge beloved by San Diego locals.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

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

Stripes of flowers bloom each spring in a 50 acre rainbow of color.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Canyon walls shrouded in ferns.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

A meditative space out of a fantasy story.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Quite simply the largest tree in the world (by volume).

Each year these high desert hills are absolutely covered with poppy flowers in a surreal show of nature.

This strange seaside tower got its name from a wealthy eccentric who would hide coins among its stones.

A strange house built only at night, with rumored mystic inspiration.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

Towering basalt columns, a creation of fire and ice.

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

The only theatre in the world constructed specifically for sound movement.

A unique set of caves that spits waves back out into the ocean.

The world's largest military aircraft cemetery.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

The world's largest rose bush has literally outgrown the pioneer museum it was planted behind.