Gargantua, the giant, is said to have used this chamber as a bed. Maybe he liked sharing his bed with a few fairies!
See – The Life of Gargantua and of Pantagruel (in French, La vie de Gargantua et de Pantagruel) a connected series of five novels written in the 16th century.
en.wikipedia.org/wiki/Gargantua_and_Pantagruel
A passage tomb known by several different names, close to Lumé, in the commune of Fargues-sur-Ourbise.
The chamber would originally have been between sixteen to eighteen meters in length, but is now reduced to only five and a half meters. There are currently half a dozen covering titles.
Official record of site from the Ministry of Culture database