Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

One man's swirling six-acre monument of stone.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

A once grand hotel is being retaken by the wilderness it once capitalized on.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

A natural gas leak provides a flickering flame beneath a waterfall.

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

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

An abandoned castle owned and ignored by Masons carries a cursed history.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

This locally-famous crevasse in New York State is icy all year round.

Explore the dark underground corridors of this graffiti-covered former military fortification.

A charming museum of natural history featuring dioramas and exhibits made entirely by college students.

An unusually designed bridge from the 1920s was built to withstand the tides and winds of Maine.

This World's Fair showpiece was built in Chicago, but shipped to Maine.

Every plane, auto, and bicycle in this collection is kept in working order and are regularly demonstrated to the public.

For nearly 200 years the same family has harvested ice from a small pond in eastern Maine.

A precariously balanced rock perches on the edge of a cliff created tens of thousands of years ago by glacial erosion.

This museum on a college campus pays tribute to the Arctic and to two explorer alumni.

A monument marks the beginning of the longest north-south road in the United States.

Walk the same tracks that once ferried Gilded Age aristocrats to their vacation destinations.

They call buildings like this "mimetic architecture," but nothing has ever mimicked the taste of Moxie.