A crumbling hospital from the 1850s on Roosevelt Island.

Waterway populated with abandoned projects, including a submarine.

The loneliest island in New York.

Surrounded by low rise buildings and partially converted into an auto body shop, this marble archway is the only vestige of a forgotten Manhattan estate.

A long abandoned hospital building on the outskirts of NYC.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

Once America's longest-manned military fort, now an abandoned hulk.

This secluded ruin was once a home for exotic plants.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

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

Long the exclusive domain of birds and vagabonds, this little-known Central Park peninsula is open to the public once more.

Read a book next to a Midtown waterfall.

Swarms of butterflies cannot compare to the awe inspired by the publicly-funded nakedness once displayed in this sunken garden.

Where there's quartz, there must be gold. Thus is the story of the mines of Julian, and the titillating times of the Gold Rush.

Stripes of flowers bloom each spring in a 50 acre rainbow of color.

What began as an illegal art installation has become a symbol for unity, ocean awareness, and coastline preservation.

This small pedestal marks the spot of the first lot of land sold in Alexandria, Virginia in 1749.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

Once forgotten and built over, this historic Black cemetery now houses a poignant memorial.

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

An abandoned stretch of highway, deteriorating next to the operational one.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

Once a thriving town of 100, Argonne was abandoned around 1970.