Corner tower

Lore & Background

Corner towers were built at the corners of castles or fortresses to compensate for the inherent weakness of wall corners. In medieval fortresses, these corners were easier to attack and more difficult to defend, and enemy combatants reaching the tops of walls at corners were protected where the walls met. The towers made it possible to provide enfilade fire against attacking forces along adjacent walls, forcing attackers to concentrate on the towers themselves where they could be dealt with more effectively.

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. Examples of corner towers can be seen on the Wall of Philip II Augustus (Tour du coin (Louvre), Tour de Nesle, Tour Barbeau), on the Wall of Charles V (Tour du Bois), in the city of Carcassonne, in the Château de Pierrefonds, and in the fortress of the Bastille.

In the architecture of non-defensive structures like churches and theater buildings, a corner tower is any tower protruding upward from the corner of two walls, usually having no walls of its own below the roof, while other towers are usually attached by one wall.

Reader's Guide

Corner towers represent a key defensive innovation in medieval fortification. Their primary significance lies in addressing the structural and tactical weakness of fortress corners, which were more vulnerable to attack and harder to defend. By placing larger, taller towers at these points, defenders could provide enfilade fire along adjacent walls, forcing attackers to engage the towers directly. The inclusion of additional defences at the base—such as ditches, fences, and advanced forts or bastions—further enhanced their protective role. The legacy of corner towers is evident in surviving examples on the Wall of Philip II Augustus, the Wall of Charles V, Carcassonne, the Château de Pierrefonds, and the Bastille. In non-defensive architecture, the term 'corner tower' also describes towers protruding from building corners, though without defensive functions. The two proposed purposes—compensating for corner weakness and enabling enfilade fire—remain as noted in the source, with no resolution of the uncertainty between them.

Did You Know?

• Wall corners were easier to attack and more difficult to defend than the rest of the walls.
• Towers at fortress corners were larger and taller than other towers, with defences such as ditches and fences at the bottom.