In 1571 and 1591, the wooden buildings were attacked by the Crimean Tatars. In 1612, the Tsar, Michael of Russia, had the monastery completely rebuilt. This included the thick stone walls which made it one of the fortified monasteries on the edge of Moscow. These new stone walls were 7.5 meters high and 2 meters thick. They were 782 meters in length, and included six towers. These are the buildings which are still standing. The bell-tower, one of the tallest in Moscow, and the Sheremetev sepulchre in the church of the Sign, were added in the 18th century,