A whimsical monument deep in this park commemorates the groups that helped build it.

Along the Palisades skyline are the ruins of a large mansion built in 1911 and demolished in the 1930s.

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

The life of one of FDR's possible mistresses is preserved in her palatial Hudson Valley mansion.

The world's largest kaleidoscope, designed by a 1960s psychedelic artist.

This once-private estate is now a dreamy, meditative garden that's open to the public.

The famous author's cottage hideaway.

The attic and basement house two museums stuffed with oddities like swallowed spoon handles and a shrunken head.

This old-fashioned candy shop, ice cream parlor, and diner served as the setting for one of TV's most controversial series finales.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

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

This mouldering abandoned mental hospital was once a center for progressive healing.

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

This stone gatehouse was once the entrance to a historic mountain resort, and it had a cameo in a cheesy cult horror movie.

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

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

These mouldering mansion ruins remember a time when the Catskills were nothing but luxury.

Historic town settled in the 19th century because of its convenient location along a popular coal transport route.

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

This Central New York ghost town was once a prosperous railroad community.