This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

This small, hidden cove is home to abandoned boats.

An abandoned subway tunnel that could have reinvigorated Staten Island still lies somewhere beneath this Brooklyn park.

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.

An impressive collection is dedicated to the legendary beast.

An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

Mansion and shopping center used in the 1975 film "The Stepford Wives."

The intriguing personal collection of a professional demon-chaser.

This eclectic homestead is home to a miniature windmill and Connecticut's last tollbooth.

The kind of mixed-up place that drives archaeologists crazy.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

Obscure Freemasons still live in D.C.’s largest private residence.

An Industrial Revolution-era public work that purified water using nothing but sand.

The world's only international cryptozoology museum is host to an unrivaled collection of mysterious objects.

A lawless town deep in Death Valley was famous for its riches and death rate.

The loneliest island in New York.

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

America's greatest forgotten garden and the former stomping grounds of Son of Sam.

A luxurious doomsday bunker hidden beneath an unassuming Las Vegas home offers the best of subterranean suburbia.

The schoolhouse where Jesse Merwin, the inspiration for the "The Legend of Sleepy Hollow" character, once taught.

Three acres of mythology-inspired sculptures are visible from the highway.

A swamp that was the site of prehistoric water burials also managed to preserve its corpses for millennia.

European castle ruins in an American state park are actually the product of death and grief.