This abandoned sea fort has become an accidental bird sanctuary.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

A dilapidated dock tells the story of Titanic's missed arrival.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

A crumbling hospital from the 1850s on Roosevelt Island.

The "lovely red Vega" of the legendary record-settling pilot.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

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

A derelict bit of transportation infrastructure hidden in the woods.

A curious sculpture garden and museum in Cochrane, Wisconsin.

Every winter, dozens of otherworldly ice structures sprout up from a rigged up artesian well.

This whimsical sculpture garden is a local treasure.

143 feet of leaping muskie whose mouth can be used as a wedding venue.

Whimsical sculptures dot a woodland path surrounding their creator's old summer cottage.

Where experiments are conducted on all things wood.

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

This former theme park in New York's Adirondack Mountains fell into ruin before being resurrected as a state-run campground

This enormous Hindu temple in Queens serves incredible dosas in its basement canteen.

From economic backbone of a community to deadly diving hole, these former stone quarries are now a park for rock climbers and graffiti artists.

Over 100 concrete munitions bunkers are all that remain of a Pennsylvanian village seized by the US government.

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

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.