The Ramparts of Senlis are located in Senlis (Oise), capital of the Oise arrondissement in France. They consist of the Gallo-Roman city walls and medieval ramparts proper.
The Gallo-Roman enclosure.
History.
The Gallo-Roman walls of Senlis 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.
Vestiges.
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. The wall can be seen from the following public spaces within Senlis: the park of the old royal château and Square Vernet near the Collégiale Saint-Frambourg de Senlis. Outside the city, the wall can be seen from the Jardin du Roy (Garden of the King) and the garden behind the old bishopric. Other traces remain of the Porte Bellon or Rheims gate in the Rue du chancelier Guérin, and of the postern in the Rue de la Treille in the arch of the "fausse porte" ("false gate"—see below).
The surviving fifteen towers of the Gallo-Roman wall are as follows, clockwise from the north:
The city gates.
The city gates in the medieval ramparts are listed below in clockwise order, from the north. The city gates did not all exist at the same time, but there were never less than four. Some confusion may result from difficulties interpreting old documents, which sometimes use synonyms to refer to the same gate, or do not clearly distinguish between a gate—open to road traffic—and a postern gate—solely used by pedestrians. None of the gates of the medieval enclosure survive today, and the only known images of them date from a period when demolition of the walls had already begun.
Between 1383 and 1402, municipal registers mention four gates: 
In 1480, a total of nine gates and posterns were enumerated. Only the Weavers' Postern Gate (des Tisserands), which still exists today, had not been built yet, nor the Porte de Compiègne. In 1544 however, the Porte aux Ânes (Donkey Gate) was one of the five gates of the city., which implies that at least one of the above gates had been either blocked off or reduced to a postern gate, at least temporarily.
Protection.
The remaining vestiges of the porte de Meaux were registered as historic monuments with a decree April 5, 1930. The medieval ramparts were added to the register of historic monuments by two decrees on May 8, 1933, one concerning the Tour du Jeu d'arc, and the other the ramparts as a whole., and the site was registered by decree on 17 December 1948. on This registration was particularly concerned with the "boulevards et promenades ceinturant la ville sur une longueur d'environ 2700 mètres " (approximately 2700m of boulevards and walkways circling the city), and included both public and private property. Also, the line of the medieval ramparts was used to define the limits of the historic preservation sector of Senlis, declared by the decree of 20 September 1965. Curiously, the areas outside the ramparts were not included in the preservation area, and restoration of the vestiges of the medieval wall was apparently not envisaged.
Vestiges.
The demolition of the Senlis fortifications primarily concerned the gates, towers, bastions, buttresses and trenches. The ramparts proper still survive for most of their length, whether in close to their original state, as they are in a few rare places, or in ruins. These ruined vestiges are entirely accessible on foot, on a moped or even in a car, where the rempart des Otages is concerned since it has been transformed into a road (Boulevard des Otages and Boulevard du Montauban). On the other hand, the vicinity of the external face of the ramparts is inaccessible to the public, as it is now made of private gardens. 
The Escalade rampart begins at the Place du 3e houzards, (3rd Hussars Place), a name given to the area surrounding the monument to Franco-Moroccan brotherhood on Cours Boutteville, not far from the Square de Verdun (a public garden in front of the old train station). It's a public promenade that runs north–south for about 250m, as far as the Meaux gate, where it becomes the Bellevue rampart. The walkway is on the rampart and since the grounds to the east are all private property, one can see very little of the walls of the enclosure. The rampart was lowered by three meters, and the trench backfilled. Even from the Rue du moulin Saint-Étienne (Street of the Saint-Étinne Mill), parallel to the Belleville rampart to the east, the rampart isn't visible until the bastion at the Porte de Meaux. The name of the Rempart de l'Escalade comes from an episode in the history of Senlis that took place after the victory against the Catholic League, on May 17, 1589. The latter did not accept their defeat but instead sent men on July 4, 1590, to scale the ramparts by night with ladders, at a moment when Henri IV and his troops were engaged in several other theaters of conflict. The first invaders were nonetheless discovered by a guard, and, thinking that the city was already invaded, he gave the alarm. So many citizens of Senlis then came to the walls' defenses, that the invaders fled as soon as the sun rose.
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The bastion of the Porte de Meaux, also known as the bastion Saint-Vincent, is perhaps the most imposing element that remains of the medieval enclosure; however it does date from the modern era. It was built in 1544 under Jean-François de La Rocque de Roberval, charged by François I with completing the city's defenses. In 1619, the archer's community received permission to establish a butt on this bastion, in return for an annual payment of four "livres", ten "sols tournois". The bastion can be seen from Rue du moulin Saint-Étienne, behind private gardens, especially when the trees have lost their leaves. It can also be seen from a different angle on the Rue de Meaux.
The rempart des Otages (Hostages' Rampart) corresponds to the boulevard des Otages (Boulevard of the Hostages), named for the hostages who were decapitated in the April 19, 1418 siege of Senlis. Boulevard des Otages goes from the site of the former porte de Paris, at the intersection of the Paris road and the old Paris road, to the western end of rue de la montagne Saint-Aignan (Mount St Aignan Street). From this point, incidentally the location of the plate-forme du Montauban (see below), the boulevard is named boulevard du Montauban. Le boulevard des Otages was built on the crown of the rampart and this is why the unprepared visitor might search in vain for the rampart. It was also built over the moat of the first medieval rampart The bridge over the Nonette leading to the Paris gate is the only place where it is possible to contemplate the rampart from outside: all the land below it is privately owned. The preserved section of the rempart is 250m long, measured from the boulevard. For this reason, nothing remains between the Porte de Paris and the elbow of the boulevard where it deviates towards the north-east. The wall overlooking the river can be considered part of the ramparts only to a point.
Notes and references.
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