Given 'It has served as a fortress for the Gallo-Romans, the Visigoths, Franks, and medieval French (you can see the layers of their masonry in the ramparts).', would 'Various people have used it as a fortress, as can be seen from the layers of masonry.' be a logical outcome?
It has served as a fortress for the Gallo-Romans, the Visigoths, Franks, and medieval French (you can see the layers of their masonry in the ramparts).###Various people have used it as a fortress, as can be seen from the layers of masonry.