Round Turret

A small round tower, usually supported by corbels, that is attached to a larger structure, usually on a corner or angle, projecting vertically from the wall of a building, usually with a steep pointed roof.

The difference between a Tower and a Turret is their base. Towers go all the way to the ground and have their own foundation. Turrets are small towers attached to a larger structure that emerge from an upper level, hanging over empty space below. Turrets are less common.