A historic 1890s architectural masterpiece with an iconic clock tower that, once open to the public, now faces an uncertain future.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

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

A collection of artifacts from Maryland's maritime past.

This abandoned sea fort has become an accidental bird sanctuary.

The land is home to swimming ponies and a legendary 18th-century treasure.

A desiccated merman and a walrus penis bone are among the oddities in this eclectic collection of shipwreck treasures.

WWII-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers. .

A grotesque Fiji merman dwells within this traditional Dutch-style building.

The historic home still shows the scars from a little run-in with the British in 1813.

The Dover International Speedway is home to a towering, concrete-skinned, racecar-hungry behemoth.

Museum houses an impressive display of the origin and artistry from the now-quaint invention's history.

What began as an art installation is now the private drinkhaüs for a brewery's employees.

A statue of the English poet for whom this Delaware town is named is ritually dressed in seasonally appropriate clothing.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

Built by the patriotic residents of Boonsboro in a single day.

This massive swimming pool is the high tech home to the human-powered submarine races.

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

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

The Virginia farm where John Wilkes Booth met his grisly end is now largely forgotten.

Under a playground is a little-known sealed train tunnel that likely contains the bodies of workers trapped by cave-ins.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.