Kumla Prison (Swedish: Anstalten Kumla) is a prison facility in Kumla Municipality, Sweden. It was opened in 1965 and is Sweden's largest prison. Kumla is one of three high security prisons in Sweden holding risk inmates (security class 1). On 18 March 2009, a new supermax facility was opened inside the Kumla Prison. Controversies. The 1972 escape of 15 inmates. On the night of 18 August 1972, between 3 am and 4 am, 15 inmates escaped from the Kumla bunker, which was considered the most escape-proof prison in Sweden.
https://en.wikipedia.org/wiki/Kumla_Prison