Topic summary
Oubliette

Extracted from the Wikipedia article Dungeon.
History
The identification of dungeons and rooms used to hold prisoners is not always a straightforward task. Alnwick Castle and Cockermouth Castle, both near England's border with Scotland, had chambers in their gatehouses which have often been interpreted as oubliettes. However, this has been challenged. These underground rooms (accessed by a door in the ceiling) were built without latrines, and since the gatehouses at Alnwick and Cockermouth provided accommodation it is unlikely that the rooms would have been used to hold prisoners. An alternative explanation was proposed, suggesting that these were strong-rooms where valuables were stored. Folklore often has it that one mode of use for oubliettes in the Borders, which would obviate latrines anyway, was to throw attackers into the oubliette, close the latch, and leave them to die. It seems likely that this gruesome act was threatened more often than it was carried out in practice, with the real aim being deterrence of potential attackers via the notoriety of the rumor that such a fate was entirely possible, and (plausibly) perhaps not unlikely, for anyone who might dare to attack.