Enormous lake at the bottom of a unique cave system.

This abandoned five-star hotel is now a five-star urban exploration destination.

A unique seaside cave where Aleister Crowley faked his own death.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

This crumbling Portuguese ruin overlooks the populace it once ruled.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

This small chapel is built of human bones and decorated with a golden skeleton.

This ramshackle ghost town is comprised of mining-era buildings collected from around the region.

This Southern Californian Conservation Center is home to singing and howling apes.

Finale of "William Tell Overture" can be heard as drivers pass over grooves in the road.

Take shelter from Hawai'i's tropical heat under the massive canopy of largest Banyan tree on the island.

From Japan to Italy, this California park explores the world's cultures through their gardens.

Where a railroad loops under or over itself to rise or drop more than 70 feet in a short distance.

Thousands of turbines whir at the origin of North American wind power.

The "3rd largest" city in California is an empty mirage of suburbia in the middle of nowhere.

Abandoned hotel with adjacent lake and golf course.

Salt is slowly eating away this abandoned saltworks town in the desert.

The liveliest ghost town in the state.

Watch the newest land on the planet form before your eyes.

In 2018, Pohoiki Road was severed by lava flowing from the eruption of Kilauea.

A series of waterfalls and pools that flow through the 'Ohe'o Gulch and into the ocean.

Hide from the tourist hordes in these relatively unknown, and unguarded lava caves.