This map, published in 1867, was made by Alexandre Bertrand, secretary of the Commission de Topographie des Gaules (CTG). The focus of this map is megalithic monuments, one of Alexandre Bertrand’s preferred areas of research. In 1862, in a paper awarded a prize by the Institut de France, he argued that these monuments were not Celtic, even though at the time many scholars still believed that dolmens and menhirs were the work of the Gauls.
This document clearly shows the CTG’s interest in periods prior to the Gallic and Gallo-Roman periods, beyond the scope of its work as initially defined by Napoleon III.