Kirillo-Belozersky Monastery (), translated into English as White Lake [translation of the town name of Beloozero] St. Cyril's Monastery, used to be the largest monastery and the strongest fortress in Northern Russia. The monastery was consecrated to the Feast of the Dormition of the Theotokos, for which cause it was sometimes referred to as the Dormition Monastery of St. Cyril. By the 20th century, the town of Kirillov had grown nearby. History The monastery was founded in 1397 on the bank of Lake Siverskoye, to the south of the town of Beloozero, in the present-day Vologda Oblast. Its founder, St. Cyril or Kirill of Beloozero, following the advice of his teacher, St. Sergius of Radonezh, first dug a cave here, then built a wooden Dormition chapel and a loghouse for other monks. Shortly before the creation of the monastery, the area fell under the control of the Grand Duchy of Moscow. Being a member of the influential Velyaminov clan of boyars, Kirill relinquished the office of father superior of the greatest cloister in medieval Moscow, the Simonov monastery. His close ties with the ruling elite can be convincingly demonstrated by his letters to sons of Dmitri Donskoi. It seems that the Muscovite rulers regarded Kirill's monastery as an important strategic point, both for Northern trade and in their struggle with the Novgorod Republic. By 1427, when Kirill died, the prince of Belozersk-Mozhaisk (subject to the Grand Prince of Moscow) was the monastery's patron, and the monastery was administratively subordinate to the Archbishop of Rostov. Under Hegumen Trifon (1434/5–1447/8), social and administrative reforms were undertaken, including the adoption of an Athonite cenobitic rule. A Byzantine-style secondary school was established at which translations of textbooks on grammar, semantics, geography, and history were used. A lasting legacy of the school were bibliographical studies, exemplified by the elder Yefrosin, and text-critical studies, exemplified by Nil Sorsky (1433–1508). Nil also founded a skete on the Sora River near the monastery. In the 16th century, the monastery was the second richest landowner in Russia, after its model, the Trinity Monastery near Moscow. Ivan the Terrible not only had his own cell in the cloister, but also planned to take monastic vows here. The cloister was also important as a political prison. Among the Muscovite politicians exiled to Kirillov were Vassian Patrikeyev, Tsar Simeon Bekbulatovich, Patriarch Nikon, and the prime minister Boris Morozov. In December 1612, the