This delightful horseshoe-shaped square was built from 1730 to 1755, based on the plans of architects Gabriel father and son. It is framed by two buildings: to the north the Palais de la Bourse, and to the south the former Hôtel des Fermes, now home to the Musée National de la Douane (National Customs Museum). The Fontaine des Trois Grâces (1860) stands in the middle of the square. Opposite, the elegant 18C façade is reflected in the city's famous miroir d'eau.