The prison was built in 1861 by the French colonists to jail those considered especially dangerous to the colonial government.
Notable prisoners held at Côn Sơn included Huỳnh Thúc Kháng from 1908–1921,[1] Phan Châu Trinh from 1908–1911, Tôn Đức Thắng, Phạm Văn Đồng and Lê Đức Thọ in the 1930s,[2] and Nguyễn An Ninh who died in the prison on 14 August 1943, possibly killed by his jailers for fear that he might be used politically by the Japanese.
In July 1970, two U.S. Congressional representatives, Augustus Hawkins and William Anderson, visited the prison.
They were accompanied by Tom Harkin (then an aide), translator Don Luce, and USAID Office of Public Safety Director Frank Walton.
When the delegation arrived at the prison, they departed from the planned tour, guided by a map drawn by a former detainee.