The existence of a wooden bridge on the site seems almost certain even before the Roman presence in Gaul. Then, around the year 872, a fortified stone bridge was recorded which constituted, for several centuries, the only crossing of the main branch of the Seine. Until 1141, the various bridges built at this location were called "Grand-Pont", as opposed to the "Petit-Pont" which spans the small branch. It was at this date that King Louis VII, by ordering that all the money changers of Paris settle there, gave it its current name of "Pont-au-Change".On October 24, 1621, a fire destroyed it from top to bottom, along with a neighboring bridge, now disappeared, the "Pont aux Colombes" or "Pont Marchant". The money changers had requested permission from the king to rebuild the structure at their own expense, on condition that they could build houses on it. This was granted by a royal edict of May 1639, with the king himself contributing to the construction costs from "extraordinary funds". This bridge, built between 1639 and 1647, had seven masonry arches, six of which were in the Seine; at 32.60m wide, it was then the widest bridge in the capital. The new bridge, the one we know today, was started in 1858 at its new location and opened to traffic on August 15, 1860. The masonry vaults incorporate cut stones from the previous bridge. The imperial "N" of Napoleon III, sculpted by Cabat, is identical to that of the Pont Saint-Michel.