This amazing ancient cave was kept secret for seven years to protect it from the public.

Stenciled handprints and wall paintings dating back 10,000 years, some of the earliest forms of cave art.

The storied steakhouse is the last in a long line of Lebanese-owned supper clubs in Tulsa.

One of the first skyscrapers in Santa Monica, and a famous getaway for the Hollywood elite of then and now.

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

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

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

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

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

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

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

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

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

Towering basalt columns, a creation of fire and ice.

The rocks in this arid basin leave trails of movement behind them.

The ghostly remains of an accidental sea.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

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

A huge musical instrument played by the ocean.