This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

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

A train tunnel that was made obsolete by the dam it helped create.

Nature (and graffiti) reclaim this old waterworks that has been surrounded by a bike path and network of walking trails.

This underground holding cell was forgotten for over a century and rediscovered in the 1960s.

Home to the abandoned Tioronda Hat Works Factory, this park is a combination of woodlands and marshlands.

Historic seaside park featuring explorable, abandoned military structures.

This abandoned iron furnace was one of the first to use coke—a type of high-carbon fuel—to make iron.

This vacant station is a relic of harvest processing techniques of the mid-20th century.

Decommissioned NYC subway cars are dumped into the ocean to create this underwater wildlife habitat.

A small wall and marker are all that remain of this historic canal tunnel.

Built by an accountant with a dream of running a grand resort, this estate has sat vacant for over half a century.

Hike deep into the woods to explore this Gilded Age masterpiece.

This advertisement for talcum powder was painted on the rock face and has since defied removal.

Francis Julius LeMoyne built this crematory in 1876; he was the third person to be cremated here.

Built around 1845, this house was occupied for 100 years, serving as a home to a prosecuting attorney, a Union Civil War general, and a wealthy socialite.

Built in the 1850s, this church was of the first five churches constructed in Harper's Ferry.

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

The last of nine massive kilns that produced many of the red bricks for buildings in Washington, D.C. and northern Virginia in the early 20th century.

A small Second Empire-style building is one of only seven remaining lighthouses on the Hudson River.

A historic bridge no one is allowed to cross.

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 beautiful hidden gem in central West Virginia.

This 15-foot tall obelisk commemorating the Philadelphia-Baltimore railroad connection sat neglected for over a century.