Asylum Architecture in the United States, including the architecture of psychiatric hospitals, affected the changing methods of treating the mentally ill in the nineteenth century: the architecture was considered part of the cure. Doctors believed that ninety percent of insanity cases were curable, but only if treated outside the home, in large-scale buildings. Nineteenth-century psychiatrists considered the architecture of asylums, especially their planning, to be one of the most powerful tools for the treatment of the insane, targeting social as well as biological factors to facilitate the treatment of mental illnesses. The construction and usage of these quasi-public buildings served to legitimize developing ideas in psychiatry. About 300 psychiatric hospitals, known at the time as insa