Threatened use of the smallpox virus in bioterrorist attacks recently prompted national concerns in the United States. Smallpox, the "speckled monster," was known in antiquity. In 1856, New York City opened its first hospital devoted to caring for victims of smallpox. Essentially, the hospital isolated and quarantined patients on Blackwell's Island, located in the East River between Manhattan and Queens. After the hospital closed about 1875, the facility became a training school for female and male nurses. In the mid 1950s, the building was abandoned. Today, the ruins of the smallpox hospital are listed on the National Register of Historic Places. At night, the ruins are illuminated casting an eerie, green aura on the remaining stone walls.