These World War I shooting range tunnels are now haunted halls of underground graffiti accessed through the roots of a tree.

A deteriorating 1990s Girl Scout camp in a beautiful lush park on Lake Ontario.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

An abandoned asylum once on the cutting edge of lobotomies may be reborn as a Christian college.

A forgotten relic from New York's bygone trolley system hides in plain sight under a bridge.

The abandoned ruins of America's first private zoo are open for exploration in the Catskills.

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

The small burial plot is located in a mall parking lot.

A 13,000-year-old mastodon skeleton was found during the construction of a 19th-century New York mill.

This stained glass window designed by Tiffany Studios is hidden behind the circulation desk of a public library.

This relic of 19th-century infrastructure is one of the few remaining coal gas storage tanks in the U.S.

The largest museum dedicated to Italian Americans on the East Coast is located in a 100-year-old church.

This giant monument of the RCA mascot is a beloved fixture in Albany, New York.

A CT scan revealed the identity of this 3,000-year-old mummy that everyone erroneously thought was female.