The story I am currently writing opens with a nun finding two dead bodies at the bottom of a concealed hole in the ground. One is a recently demised corpse which has been thrown on top of another victim’s charred remains. What a lovely imagination I have! Anyway, in true Charlie style, I have adapted this idea of an underground cell to suit my own purposes, but the idea is based on an oubliette; a torture chamber taken straight out of the Medieval Ages. It is more commonly held nowadays that such cruel usage only came into being during the 15th/16th centuries and went on to become a popular topic of nineteenth century gothic fiction. It is, however, far more likely that in Medieval times they were used as basement storerooms, water-cisterns or latrines.
Oubliette means a little place of forgetting. The prisoner would have been lowered by a rope into a small vertical space with only room to stand up; no sitting, kneeling or turning around. The rope was then taken away and the trap door (angstioch) closed with the person unable to reach it and therefore they were left alone and in complete darkness. There they would have stayed (at the mercy of a forgetful jailer who often left them to starve to death) before the next poor victim was thrown on top of their corpse. Utterly terrifying.
A fine example of an oubliette can be found in Caesar's Tower at Warwick Castle.