The scene where George Chakiris, Grover Dale and company dance on a bridge was shot on the Rochefort-Martrou Transporter Bridge, one of less than 24 transporter bridges ever built. A transporter bridge (also ferry bridge or aerial transfer bridge) is a type of movable bridge that carries a segment of roadway across a river. It is one of only 12 that continue to be used as of 2014.
Before Jacques Demy selected Rochefort as the location for this movie, he also considered Avignon, Hyeres, Toulouse, and La Rochelle among others. Rochefort won out because of the size of its central square, though production designer Bernard Evein found it necessary to repaint 40,000 square meters of the city's facades.