Rue Cambon became the Paris street associated with Coco Chanel’s famous flagship boutique.
Chanel established her major Paris presence on Rue Cambon, where number 31 became the house’s celebrated couture address. The building brought together important parts of her business: a boutique, couture workrooms and the designer’s private apartment above.
The question asks for the street rather than the building number. Rue Cambon is the canonical answer because the Chanel house and its history are closely tied to the location. Number 31 is often mentioned alongside the street, but it is not the street’s name.
Paris fashion is also strongly associated with Avenue Montaigne and other prestigious shopping districts. Those locations are important to other couture houses, but Rue Cambon is the address most specifically linked with Coco Chanel’s own fashion headquarters.