For over a century, it was a crucial center of mental health treatment and also the source of many local legends.

Paranormal investigators claim this abandoned asylum is the most haunted spot in the eastern U.S.

One of the largest-ever mental hospitals now sits abandoned, surrounded by 25,000 unmarked graves.

Once America’s most beautiful army base, this abandoned military fort on the coast of Monterey Bay has been left to the elements.

An iconic steel and chrome diner from the 1940s left empty for nearly 20 years is in danger of being demolished.

An eight-sided home built during a brief octagon craze in the 1850s.

A long-vacant Scottish Rite temple in Hollywood has been converted into an art museum filled with Masonic relics.

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

The ruins of a 19th century shelter run by the Independent Order of Odd Fellows.

The remains of a century-old mansion that met a fiery demise years after it was deserted.

A historic recreation of the golden age of the Erie Canal, abandoned for some time, slowly being restored.

A remarkable time capsule of American manufacturing deep in Maryland coal country.

A recently abandoned psych ward at the end of Sanatorium Road.

Portland had a unique approach to Cold War-era protections.

This little gem of Spanish Colonial architecture has been abandoned since the 1950s.

An abandoned Depression-era zoo hidden just off the highway.

A mammoth pair of Civil War artillery guns abandoned out in the forest.

These recently uncovered walls are all that's left of Washington, D.C's first defense contractor.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

Once the world's largest reinforced concrete structure, this abandoned bridge now beckons urban explorers.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

An abandoned railroad tunnel forgotten by time awaits inquisitive hikers.

An unrealized Taoist palace left abandoned in a Houston suburb.

The overgrown ruins of a once thriving World War I-era copper mine.