Roubaix (French: [ʁubɛ] or [ʁube]; Dutch: Robaais; West Flemish: Roboais) is a city in northern France, located in the Lille metropolitan area on the Belgian border. It is a historically mono-industrial commune in the Nord department, which grew rapidly in the 19th century from its textile industries, with most of the same characteristic features as those of English and American boom towns. This former new town has faced many challenges linked to deindustrialisation such as urban decay, with their related economic and social implications, since its major industries fell into decline by the middle of the 1970s. Located to the northeast of Lille, adjacent to Tourcoing, Roubaix is the chef-lieu of two cantons and the third largest city in the French region of Hauts-de-France ranked by population with nearly 99,000 inhabitants.

Together with the nearby cities of Lille, Tourcoing, Villeneuve-d'Ascq and eighty-six other communes, Roubaix gives structure to a four-centred metropolitan area inhabited by more than 1.1 million people: the European Metropolis of Lille. To a greater extent, Roubaix is in the center of a vast conurbation formed with the Belgian cities of Mouscron, Kortrijk and Tournai, which gave birth to the first European Grouping of Territorial Cooperation in January 2008, Lille–Kortrijk–Tournai with an aggregate population of over 2 million inhabitants.