Defensive element of the medieval and ancient fortifications in the form of high-altitude structures designed to defend the front side and defend the wings of the adjacent section of the defensive circuit. The flanking towers were made of different materials: wood, stone or brick, or in mixed construction. Architectural style of the tower was varied depending on the need and time of the emergence, it could have a quadrilateral, polygonal, circular, semicircular and other form, sometimes variable in each floor. The flanking towers were of different sizes: from small 2-3 meters and 1-2 storeys, to large size buildings: 10-20 meters in diameter and 5-6 storeys. The towers could be both protruding in the front and connected to the circuit by the neck as well as barely extended from the perimeter line. In relation to its interior can be closed, accessible from the guard porch, open partly by an arcade, or completely without a rear wall. Typical defense equipment included arrowslits of various types, machicolations or hoarding, and battlement.