Scattered around western France, in the area roughly defined by Limoges, Poitiers and S. Jean d’Angely, are small mediaeval stone towers with an opening at the top once used to display a light at night, and with a hollow interior to allow access to the top. Right down to today, they are often associated with a cemetery. Examples like that at Bisley (Glos, ND Nov. 2017) are exceptionally rare in England. Their purpose seems to have been a living memorial to the dead in an age of nameless graves, at a time before gravestones. A 12th c. Abbot of Cluny, Peter the Venerable, wrote: “What occupies the middle of the cemetery is a stone building. It has at its top a cavity which can hold a lamp which, in honour of the faithful who rest there, illuminates this consecrated place every night.” They have become known as Lanternes des morts (Lanterns of the dead).
The square tower at Antigny (Vienne) has a doorway in its north side giving access to the interior; it stands in a grassy area which was once the cemetery, opposite the church. The example at Chateau-Larcher (Vienne) in contrast is cylindrical in shape, again with a doorway in its north side; it does stand in the cemetery. Perhaps the best is at Fenioux (Charente-Maritime), which is 100 metres to the west of the church, standing in an abandoned cemetery. It has eleven columns supporting thirteen colonettes which in turn support the lantern chamber.
Bibliography: John Bate, Lanterns for the Dead, Lapridge,
Hereford, 1998; http://cfpphr.free.fr/lanternedesmorts.htm;
http://www.kuriositas.com/2017/08/the-lanterns-of-dead.html