The Ramparts of Senlis consist of the Gallo-Roman city walls and medieval ramparts proper. The Gallo-Roman walls are some of the best-preserved of northern Gaul. It has so far not been possible to determine when they were built, but it was however established in the 19th century that they were built after the passage of the Germanic hordes in 275-276, and after 278. But construction could have taken place anytime after that up to the beginning of the 4th century. Given research conducted on Roman walls in other European cities, we know that those in Senlis could have been built in two good years, including all of the towers.
A second construction campaign took place starting in 500 AD, focused on raising the towers with rooms. Dismantling began in 1170 with construction of Saint-Frambourg, in other words, before the medieval enclosure was built.
Three quarters of the area of the Gallo-Roman castrum has been lost, and the construction from the Middle Ages, with its cellars and underground quarries has left only the tiniest of traces. The remainder notably corresponds to large public places and to a few private gardens, which have to date been only very partially excavated. The layout or spatial organisation of the Augustomagus of antiquity still remains unknown. The wall comprises the principal remainder of the Gallo-Roman stronghold. It is to a large extent surrounded by private property.
References:
