I’m currently designing a keep for my players to explore. It will be a ruined keep, taken over by an evil cult. But to start off the design, I am looking at how it would have been designed in its prime. Here are some rooms I’ve thought of when creating the layout.
Military function
- Armory
- Smithy
- Fletcher
- Training room
- Lookout posts
- Infirmary/Hospital wing
- Gatehouse
- Barbican
- Place of Arms
- Commander quarters
- Guard bunks
Every day operation
- Great hall (mess hall)
- Steward’s Office
- Clerks/Tax assessors/Scribes Office
- Kitchen
- Distillery
- Scullery
- Larder/Storeroom/Cellar/Ice House
- Servant quarters
- Bathroom
- Well/Cistern
- Dovecote
- Stables
- Kennels
- Courtyard
- Gardens
Political function
- Hall of Justice
- Dungeon/Prison/Oubliette/Tower
- Throne Room
- Vault/Treasury
Noble quarters
- Drawing Room
- Bower
- Rooms for the Lord/Lady
- Formal sitting room
- Informal sitting room
- Private study
- Personal library
- Private dining room
Research
- Library
- Alchemy lab
- Solarium
- Wizards quarters
Religious
- Temple/Church
- Clergy quarters
Can you think of some more?
Editing to add the suggestions from the comments.
More detail: The cesspits will usually be placed outside the walls (and away from the water storage) of the castle and the garderobes were often placed in the outer walls with a shaft leading to the outside of the castle.