The Holy Trinity-St. Sergius Lavra, the jewel of Sergiev Possad and a UNESCO World Heritage Site, boasts two cathedrals, nine churches, a museum and several monastic buildings, sheltered behind imposing walls. Founded in the 14C by Sergius of Radonezh, the monastery was immensely prosperous and thus able to call upon great artists such as Andrei Rublev and Daniil Chernyi. In the centre of the 1,500m-long fortifying walls rises Dormition Cathedral, one of the most beautiful churches of Russia.