Solovetsky Monastery built
1401 CE.
Shown on the map at 65.024°, 35.711°.
The Solovetsky Monastery (Russian: Солове́цкий монасты́рь, IPA: [səlɐˈvʲɛtskʲɪj mənɐˈstɨrʲ]) is a fortified monastery located on the Solovetsky Islands in the White Sea in northern Russia. It was one of the largest Christian citadels in northern Russia before it was converted into a Soviet prison and labor camp in 1926 to 1939, and served as a prototype for the camps of the Gulag system. The monastery has experienced several major changes and military sieges. Its most important structures date from the 16th century, when Filip Kolychev was its hegumen (comparable to an abbot).
Text from the Wikipedia article Solovetsky Monastery, licensed CC BY-SA 4.0.