A mysterious hole in Paris

Musée de Cluny, musée national du Moyen Age, Paris, France. This plaque tells the story of a hole in the ground found in 1676. It used to lead to a cave described as a "big hole". The hole in the ground was then covered up using wooden beams, and the plaque tells us that its own purpose is to remind people to check the beams from time to time and to replace them if they are rotten. This plaque used to be located in a convent called Couvent des Mathurins (destroyed in 1860) and the plaque is now located in the Musée de Cluny, very close to where the Convent used to stand. Unfortunately, the location of the whole seems to have been forgotten. Even if it's probably not that interesting (there are lots of holes and tunnels under Paris, including ancient mines), I like to think of this plaque as the beginning of a lovecraftian story : who know what could be hiding in that mystérious hole... 3D scanned using Agisoft Photoscan. The 3D model is free but commercial use is not allowed.