A wild west land agreement was etched right onto this historic Idaho stone.

The warmest cave in the Ozarks features two seemingly bottomless lakes.

People of the Plum Bayou culture built these enormous mounds over 1,000 years ago.

These waterfalls can be twins or triplets, depending on how much it's rained recently.

Peak named for an old man who liked to run in the nude.

Home to a seasonal waterfall and swimming hole in the Ouachita Mountains.

The scant remains of an expansive indigenous civilization can be seen at this Arkansas state park.

This century-old roadside attraction is full of bizarre rock formations.

Claims to be the "World's Highest Hill."

Where hills of dirt conceal the burial ground of one of the most powerful ancient Native American societies.

Travel through the hidden underbelly of the city in colorful tunnels filled with art and history exhibits.

At the most northwestern point of the contiguous United States lies a trail leading through an ancient forest to stunning cliff-side vistas and massive oceanside caves.

Mysterious ancient petroglyphs carved on a glacial boulder at the tip of Bainbridge Island.

This large Sitka spruce that appears to be floating in mid-air, has defied logic for years.

A surreal landscape where fanged rocks rise from the ground and the ocean feels like a great mystery.

Peruse rare tomes like poetry bound in pearls or books with branches and berries growing out of their spines.

A colorful architectural gem in Seattle's uniquely modern Central Library.

This semi-secret garden in south Seattle emulates a traditional Japanese garden using the plants of the Pacific Northwest.

A peculiar forest that was handcrafted for government experiments.

Less a museum than a bizarre fantasy world created by artists and engineers.

Colorado's oldest church is now home to the largest handmade adobe labyrinth in the world.

A young state senator's deathbed plea to be buried inside a rock resulted in this unusual grave site.

A mysterious light floating in the trees of Arkansas may be a piezoelectric effect.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.