Defensive towers built at the corners of castles or fortresse
The corner towers were
defensive towers built at the corners of castles or fortresses.
Purpose
Two ideas have been advanced about the purpose or value of corner towers in medieval fortresses:
The corners of a medieval fortress were weak points because they were easier to attack and more difficult to defend than the rest of the walls. Not only this, but enemy combatants that reached the tops of walls at the corners were protected at the point where the walls met, making it more difficult to repulse them. Fortress corner towers were therefore constructed to make up for this vulnerability.
These towers made possible to provide
enfilade fire against attacking forces along adjacent walls. This would oblige attackers to concentrate some of their force on the corner towers themselves where they could be dealt with more effectively.[1]
Towers constructed at fortress corners were larger and taller than other towers. At the bottom of these towers were defences, such as
ditches, fences, and sometimes advanced forts or
bastions.
[2]
In architecture of non-defensive structures, like churches and theater buildings, a corner tower is any tower that is protruding upwards from the corner of two walls, and usually has no walls of its own below the roof. While other towers are usually attached to the building by one wall.
References
Wikimedia Commons has media related to Corner towers.
^Thompson, A. Hamilton (2013-04-10). The English Castle: An Account of Its Development as a Military Structure.
ISBN978-0486164342.