Antonievo-Siysky Monastery (Антониев-Сийский монастырь in Russian) is a Russian Orthodox monastery that was founded by Saint Anthony of Siya deep in the woods, 90 km to the south of Kholmogory, in 1520. Following the saint's death in 1556, the monastery grew on the salt trade with Western Europe and developed into one of the foremost centres of Christianity in the Russian North. Ivan the Terrible and his son Feodor granted it important privileges and much land. By 1579, the monastery owned 50 versts of ploughlands stretching towards Kargopol.