The Metropolitan Tower, which is the cylindrical part of the Novgorod Detinets, is a monument of military-defensive architecture from the 15th century. It has a round shape, is not passable, with a diameter of 13.6 m and wall thickness of 3.1 m. The height of the walls reaches 16.3 m, and the rubble foundations are laid to a depth of 3.5 m. The tower was built in 1484 and 1499, possibly on an older foundation. It is topped with a ten-meter tent, restored according to descriptions from the 17th century. The walls facing the moat are pierced with three tiers of vaulted loopholes from the 15th century. The tiers inside the tower are divided by wooden platforms connected by stairs.