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

Hidden deep within New Jersey Pine Barrens is a massive graffiti wonderland.

Inside a state forest, the forgotten remains of a Cold War defensive installation.

Tucked behind New Jersey's abandoned Gingerbread Castle lie the eerie ruins of a once-flourishing paper mill.

An allegedly cursed tree represents a town's reckoning with a racist past.

A once grand hotel is being retaken by the wilderness it once capitalized on.

The ancient past meets the retro-future at these dinosaur tracks that are protected by a geodesic dome.

A historic covered bridge is but one example of an oddly prevalent American urban legend.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

One of the first commercially successful anthracite-powered iron-making operations in North America.

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

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

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

This tiny New Jersey village has lived many lives but seems determined to remain a ghost town.

Once in a state of dilapidation, this candy-inspired fortress is now being revived.