>The structure consists of some 60 massive granite monoliths, set directly onto the bedrock in pairs at regular intervals. Smaller slabs and packing stones fill in the gaps, locking the whole into a single, deliberate construction. With an estimated total mass of around 3,300 tons, this is the largest underwater structure ever discovered in France.

Hunter Gatherers built it with all the time they had between hunting and gathering. They used their bare hands to heave 60 massive granite monoliths into place 1000 years before the Great Pyramids of Giza.

Madness....