Prisoners in the castle: dungeons and oubliettes

Medieval castles and dungeons tend to go together in people's imaginations and I have set important scenes in A Knight's Enchantment in a dungeon, where the heroine Joanna's father is being held. What we imagine as a typical dungeon, however - dark, underground, no windows, lots of chains - was less common in the Middle Ages than is assumed.

Take the word 'dungeon'. Its earliest form, donjon, meant a keep or tower, a strong defensive position. Over time that tower has been taken to mean a pri...