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.

New York City's smallest piece of private property.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

This little museum is built on a theater that was once a wildly elaborate speakeasy.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

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

Reforestation in action is the main attraction in this abandoned quarry.

This abandoned ironworks was once the most important military supplier in America.

American artist J. Alden Weir purchased this 60-acre estate for $10 and a painting.

The mysterious headstone of an unidentified bank robber was seen visited, every year, by a woman in black.

House used in the 1971 horror film "Let's Scare Jessica to Death."

This miniature feudal castle was built on a whim to honor a US Navy pioneer.

The only surviving building of historic West Boylston, which was flooded to create the Wachusett Reservoir.

One of the oldest baseball fields in continuous use has been hosting games since 1878.

This dam in the woods, built by Henry Ford with only manpower and oxen, holds no water and serves no purpose.

This railroad tunnel was once the longest in Massachusetts.

All that remains of the Whittall mansion are the ruins of the formal garden and its pergola, dedicated to the late Matthew J. Whittall by his widow.

New York City's only preserved family home from the 19th century.

A terrific purveyor of natural history objects and curios.

Underneath the bustling city streets, a hydroponic farm grows unique herbs in an urban oasis.

One of the earliest bowling lanes in the U.S. doubled as a sewing school during a time when women had little job opportunity.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.