Millhaven Institution (French: Établissement de Millhaven) is a maximum security prison located in Bath, Ontario. Approximately 500 inmates are incarcerated at Millhaven. Opened in 1971, Millhaven was originally built to replace Ontario's other aging maximum security prison, Kingston Penitentiary in Kingston Ontario. A riot at Kingston Penitentiary forced Millhaven to open prematurely. During the period of 1977–1984, a Special Handling Unit (SHU) operated at Millhaven, alongside its general maximum-security population. A new Canada-wide Special Handling Unit was subsequently opened in Sainte-Anne-des-Plaines Quebec, and the Millhaven SHU was closed.