Across the river on the south bank stood another huge tower, best known by its later name, the Tour de Nesle. It was from this tower, that, in the fourteenth century, Jeanne of Burgundy, widow of Philip the Long, is reputed to have had the people who displeased her dropped into the river. Villon’s “Ballad of Old-Time Ladies” says: “And where, I pray you, is the Queen, Who willed that Buridan should steer Sewed in a sack’s mouth, down the Seine?” Buridan was a professor in the University, and the author of the famous assertion that if an ass were placed between two equally attractive bundles of hay he would starve to death before he could determine which one to eat first. The tale goes that Buridan’s friends, fearing the outcome of his visit to the tower, were waiting in a boat and rescued him. Dumas’ play, “La Tour de Nesle” is based on the legends surrounding this old fortification, now existent only in a tablet placed on the eastern wing of the Institute to mark its site. A chain across the stream from the Louvre to the Tour de Nesle regulated navigation, for it could only be taken down for the passage of boats by permission of the provost. Starting south from the Tour de Nesle ran [Illustration: TOUR DE NESLE IN 1661.] the wall whose erection Philip commanded when he first went off to the wars, that his fair city might be well protected in his absence. It was higher and heavier than its predecessors, with a battlemented top to hide soldiers in action and frequent towers which served the triple purpose of sheltering extra men, of storing weapons and of affording points of observation somewhat above the wall itself. A dozen gates opened each upon a drawbridge whose lifting compelled the invader to cross a ditch in some way before he attempted to storm an entrance. Leaving the Tour de Nesle the wall swept around Mont Sainte Geneviève and back to the river at a point about opposite the center of the present Île Saint Louis, east of the Cité. On the right bank it ran north and west, keeping below the Priory of Saint Martin which lay outside of it. Its course is traced on the pavement of the eastern courtyard of the present Louvre, part of one of the towers is extant in a government pawnshop in the Marais, a considerable section is to be seen in the enclosure beside Saint Julien-le-Pauvre, and its course is marked elsewhere by an occasional fragment, by some street named _Fossé_, or by a tablet placed by the Commission of Old Paris, which is doing excellent antiquarian work in the preservation and marking of historic buildings and localities.