Ancient earthworks

This picture, one of a pair of stereoviews taken in the 1860s, is one of the earliest known photographs to include Grève de Lecq tower. In the background is Castel de Lecq, a much older defensive work. The picture is marked on its reverse side, Sorel Point, but this was clearly an error on the part of the photographer, or whoever later came into possession of the picture and attempted to identify it