This forgotten graveyard in rural New York State once served a pioneering hospital.

Beneath the mossy overgrowth covering this once-sprawling campus lies decades of history and the secrets that come with it.

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

An abandoned Gold Coast-era mansion once intended for the exiled ruler of Albania, who never arrived.

The abandoned grounds and derelict greenhouses of this once-magnificent Edwardian estate are now a nature preserve open for exploration.

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

This outpost of America's most popular fast-food restaurant is housed inside a palatial mansion.