Solovetsky Monastery (Russian: Солове́цкий монасты́рь; IPA: [səlɐˈvʲɛtskʲɪj mənɐˈstɨrʲ]) was the greatest citadel of Christianity in the Russian North before being turned into a special Soviet prison and labor camp (1926–1939), which served as a prototype for the Gulag system. Situated on the Solovetsky Islands in the White Sea, the monastery braved many changes of fortune and military sieges.