This gate owes its name to the earlier presence of windmills which were built outside the city walls in order to benefit from the wind (the "bel'air" which has given its name to the square (place Bel Air). The gate is part of the fortifications built between 1642 and 1647 to the south of the urban limits. The war-like decor evokes the outcome of the Thirty Years War between France and Spain, a denouement that favoured France. Trophies of weapons, plumed helmets and enemies in chains make of this gate a monument to the glorious victories of the monarchy, a gate that evokes the triumphal arches of the Roman period. Hammered out during the Revolution, the coat of arms of the King was set in the centre of the pediment.
Originally formed by a gateway for carts and carriages, and two smaller ones for pedestrians, it was transformed in 1855 by military engineers who added a second carriage gate and removed the drawbridge.
Former Gate of the Windmills (Destroyed) :
This was the principal gate to the south of the city. Built in the middle of the 14th century, the gate known as "du Moulin-a-Vent" was destroyed in 1857. During three centuries it co-existed with the present Porte de Moulins built further to the south in 1647. In a quadrangular form and equipped with a guardroom and a Gothic arch, it opened onto the former cardo maximus of the Gallo-Roman town (today's rue Diderot). This North-South axis has been since this time the major thoroughfare. Lined mostly by dwellings from the 17th and 18th centuries, the majority have now a commercial use on the ground floor (shops etc).