Donjon vs. Keep — What's the Difference?

The term 'donjon' is derived from the French language, specifically referring to the central, most secure tower of a medieval castle. This structure was primarily intended for the lord's residence and as a last resort of defense during sieges. On the other hand, the 'keep' is an English term that generally describes the main tower or fortress within a castle, emphasizing its role as a stronghold where people could retreat to safety in times of attack.

Historically, donjons were often built with massive stone walls and were designed to be impenetrable. These structures typically contained living quarters, storage for weapons and supplies, and sometimes a dungeon. Whereas the keep, while also built robustly, served multiple functions including administrative centers, residences, and military bases, reflecting its role as the nerve center of a castle.

In architectural terms, donjons were usually tall and narrow, optimizing the defensive capabilities and the ability to watch over surrounding areas. In contrast, keeps could vary significantly in shape and size but were generally larger to accommodate various functions and often formed the core of castle defenses.

During the medieval period, the evolution of military architecture saw the transition from donjons being the main feature of castles to more complex designs where the keep became more prominent. Keeps became more integrated into the castle's defensive walls and complex, whereas donjons remained as distinct, standalone structures.

In modern times, the distinction has somewhat blurred in popular usage, but traditionally, donjons were more focused on defense and residential functions within their thick, tall walls. On the other hand, keeps, especially in larger castles, evolved into more elaborate structures that could host larger garrisons, hold court, and manage estates.