The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The sign at the garden gate reads: "These Plants Can Kill."

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A toxic ghost town sitting atop a massive coal fire.

Stroll through a wonderland of stupendous moss-covered trees.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

Hot springs monkey spa in the middle of Hell's Valley.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

The fairy tale castle of the "fairy-tale king."

Enormous lake at the bottom of a unique cave system.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

Medicinal spa created with the discharge from a geothermal energy plant.

Notorious artist squat renovated into legal studios.

Resting place of Hollywood's immortals is also site of summer film screenings.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

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

Abandoned railway line circling the city of Paris.

Elevated freight railway turned wildly successful urban park.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

A collection of oddities including Dr. Kevorkian's suicide device, the Thanatron.