The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

A crumbling hospital from the 1850s on Roosevelt Island.

Site of the first pathological and bacteriological research facility in the United States.

One of only two commuter aerial tramways in the United States.

Once considered the height of medical modernity, this structure is now the oldest remaining component of Roosevelt Hospital.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Try not to get slimed in Tribeca.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

It specializes in outsider art and artifacts of secret societies.

A popular swimming hole that hides one of America's most deadly diving spots.

Now abandoned, this East Austin school for the disabled began as the "State Colony for the Feeble-minded."

A health museum containing a 27’’½-foot intestine.

This symbolic piece of New Orleans architecture is also home to a few ghastly stories.

The curiosities and wonders of pharmacy in a delightful historic building.