After a couple of days traveling—with a pleasant stopover in the Mayenne department—we arrive in the heart of southern Armorica to immerse ourselves in the landscape stretching between the Gulf of Morbihan and the Bay of Quiberon. We have thus arrived at one of the most complex and fascinating megalithic concentrations of European prehistory, recognized in 2025 as a UNESCO World Heritage Site (“The Megaliths of Carnac and of the Shores of Morbihan”).
It was here that two major streams of colonizing farmers met after centuries of moving across a continent increasingly freed from ice. Originating in Mesopotamia and Anatolia, these populations followed two distinct routes: one headed toward northern Europe (eventually reaching Great Britain), while the other followed the northern coast of Africa, crossing Spain and Portugal. Around the 5th millennium BCE, these two migration paths intersected here—where local human groups had already been settled since the 8th millennium BCE—giving rise to a dynamic culture rich in technical knowledge. They shaped the territory with a dense network of dry-stone architecture, passage graves, giant tumuli, and standing stones designed to intertwine ceremonial, territorial, and likely astronomical functions.
The moment we entered southern Brittany, megaliths immediately began popping up along our route, constantly surprising us. Every site is not only clearly signposted (with directions starting right from the national highways) but also impeccably maintained and often staffed—with attendants, guides, and well-stocked bookshops—even when access is completely free!
A prime example is the Tumulus of La Roche aux Fées, the very first site we visited. Tucked away in the countryside along the road from Rennes to Vannes—just past the magical Forest of Brocéliande, legendary home of Merlin the Wizard—La Roche aux Fées was a delightful stop. It is the largest passage tomb (allée couverte) in France, constructed from 40 massive blocks of red schist, some weighing over 40 tons! Its astronomical alignment is clearly oriented toward the sunrise of the winter solstice.
Having reached Brittany, we suggest exploring this vast region through two places that serve as essential pieces of the prehistoric landscape: the Cairn of Petit Mont in Arzon and the monumental sacredness of the Erdeven alignments.
The Cairn of Petit Mont: Evolving Architecture on the Rhuys Peninsula
Perched 36 meters above sea level on the Rhuys Peninsula, the Cairn of Petit Mont dominates the Atlantic coastline and the entrance to the Gulf of Morbihan. Since prehistoric times, it served as a crucial visual landmark for coastal navigation and territorial control. The site is extremely welcoming, featuring a well-stocked bookshop and a visitor center with informational panels alongside a dedicated workshop area for adults and children. If you visit, plan to spend a full day here: you can participate in hands-on workshops or even watch a practical demonstration on how menhirs were transported and erected in antiquity!
The initial construction phase of Petit Mont dates back to around 4600 BCE, beginning as an elongated earthen monument without internal burial chambers. Around 4000 BCE, a monumental dry-stone cairn with a long passage tomb was added beside it. During the Late Neolithic (3000 BCE), the structure was expanded to include two additional dolmen chambers, enclosed by a double stone retaining wall. Occupied through the Bronze and Iron Ages, the cairn was partially destroyed during World War II when the German occupation converted part of the ancient structure into a reinforced concrete military bunker.
The site’s importance lies primarily in its role as a spatial marker for the entire surrounding landscape, but also in the significant artifacts recovered here. These include personal ornaments made of variscite originating from Spain and a serpentine stone necklace from the Treviso region in northern Italy! Such finds provide clear clues that this funereal complex served an elite class with extensive trade connections across Europe, illustrating a vibrant and interconnected Neolithic world. This picture becomes even more intriguing when we expand our view to the princely burials of Locmariaquer or the Carnac alignments. But first, let us cross the Bay of Morbihan and travel from Arzon to Erdeven!
Erdeven and the Kerzerho Alignments: A Truly Sacred Forest!
If you climb to the highest point of Petit Mont (which was meticulously reconstructed following strict archaeological standards after wartime damage), you can admire a vast horizon and spot the peninsula on the opposite side of the narrow strait enclosing the gulf, where the megaliths of Erdeven are located. Six thousand years ago, the Gulf of Morbihan did not exist as it does today; sea levels were different, and three major rivers carved through this coastal zone.
Therefore, to reach the opposite shore today, we had to drive all the way around the gulf!
Erdeven represents one of the most spectacular and intricate standing stone complexes in the entire region. While the famous stone rows of Carnac draw most of the crowd, the site of Kerzerho in Erdeven astounds visitors with the sheer majesty of its menhirs and the complex spatial grid woven into the landscape. You can explore this clean and pristine landscape on foot in a truly magical atmosphere along a 10 km walking trail that winds among various megalithic monuments scattered all around you.
The Kerzerho alignments consist of dozens of granite monoliths arranged in parallel rows and circular enclosures surrounded by vegetation. At the edge of the complex stand impressive menhirs that remain upright—some exceeding 6 meters in height—bearing witness to a coordinated engineering and community effort during the Middle Neolithic. Much like the neighboring Carnac rows, the layout at Kerzerho aligns with key axes of the solar and solstitial cycles. These arrangements point toward a sacred landscape, likely experienced through processional avenues and open-air sanctuaries designed for community gatherings and seasonal ceremonies.
Wall Symbology, Astronomical Orientations, and the Cosmos
In our view, the spatial organization of Morbihan’s monuments reveals rigorous geometric and astronomical planning, even if current trends among archaeologists tend to downplay (or even deny) this aspect. This approach left us somewhat amazed, and we will dedicate a specific article in this series to the topic.
In any case, solstitial alignments remain evident—such as the entrances to the Petit Mont dolmens, which maintain a consistent East/South-East orientation referencing the solar cycle and cults of funereal rebirth. Visual networks are another major highlight: the elevated position of the Cairn of Petit Mont ensures direct visibility with the Cairn of Gavrinis and the megalithic enclosure of Er Lannic, integrating the entire Gulf basin into a single visually connected ritual space.
These last two sites will be the main subjects of our next article, where we will also examine ancient carvings that have survived the passage of time—bearing symbols that remain to be fully deciphered.
In the next article (Journey to Morbihan #3), we will move to Locmariaquer to analyze the sheer gigantism of the Grand Menhir Brisé and the extraordinary history of the reused stele shared between the Table des Marchands and Gavrinis.