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

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

A crumbling hospital from the 1850s on Roosevelt Island.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

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

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A terrific purveyor of natural history objects and curios.

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

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

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Astounding collection of coin-operated games and automata.

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

More gold than anywhere else, ever.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

Tucked in the back of this amazing antique store is an important piece of medical history.

Elevated freight railway turned wildly successful urban park.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.