In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

Rare recess caves fill this unbelievably beautiful Ohio park.

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).

The largest earthwork effigy in the world.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

Welcome to old Florida, where a 1940s mermaid show is still enchanting visitors.

One person's lost luggage is another person's treasure.

Towering basalt columns, a creation of fire and ice.

A self-built castle made by a mysterious man.

A beautiful geyser under environmental threat.

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

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Just a few miles from downtown Atlanta is a trail covered in a crazy collection of outsider art.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

A 100-year-old purveyor of curiosities, curios, and kitsch featuring mummies, shrunken heads, and a Fiji Mermaid.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

An enormous, inside-out glass globe built in 1935.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.