donjon

Donjon refers to the principal fortified keep of a medieval castle or fortress. It is typically the central, strongest tower or building within the fortification and often the tallest structure in the complex. Historically, the donjon functioned as the residence of the lord and as a last line of defense during a siege, while the surrounding curtain walls, gates, and other towers provided additional protection.

Etymology and usage establish the term as Old French in origin. In English, donjon is now largely archaic and is usually understood as the keep or main residence, distinct from the dungeon, which is a subterranean or prison-like space. The two words share a common historical lineage, though their modern senses differ in everyday usage.

Architecturally, donjons vary in plan but commonly feature thick stone walls, limited or narrow windows, and a secure entry. Access is typically via a gatehouse or external passage, with internal vertical circulation often provided by a spiral staircase leading to upper chambers. The upper floors housed living quarters, the great hall, storerooms, and sometimes the armory, with the tower serving both as residence and strongpoint.

Historically, the donjon was a central element of castle organization from the early to late medieval period, complementing other defensive and administrative components. While some fortresses reduced its residential role over time, the donjon remained a symbol of authority and security, offering shelter, storage, and command during threat episodes.

In modern contexts, the term is mainly of historical or scholarly interest. In archaeology and heritage interpretation, it is identified as the keep; in literature and games, donjon is sometimes used to evoke a medieval fortress or a dungeon-like setting.