Morbihan
Morbihan is a départment in the Brittany region of northwest France, named after a small inland sea on its coast. It arguably home the largest number and most spectacular megalithic monuments in Europe(a), including the alignments at Carnac.
Various commentators, with varying degrees of enthusiasm, have sought to link Morbihan and its megalithic remains with Atlantis. These include Jean Markale, Helmut Tributsch, Hans-Pény Hirmenech, Hank Harrison and the late R.Cedric Leonard. Alfred deGrazia and Helmut Tributsch saw Megalithic Europe as Atlantis with the island of Gavrinis in Brittany as its capital. Harrison considers the Morbihan départment as a significant Atlantean location, if not the home of its capital.
Felice Vinci has proposed in a 2024 paper(b) that the Pillars of Hercules were situated at Morbihan, which he claims was the starting point for transatlantic voyages by the megalith builders
(a) Morbihan (56) including Carnac (Departement) — The Modern Antiquarian
(b) https://lupinepublishers.com/anthropological-and-archaeological-sciences/pdf/JAAS.MS.ID.000314.pdf