Paris
Bal-musette is a style of French music and dance that first became popular in Paris in the 1870s and 1880s; by 1880 Paris had some 150 dance halls in the working-class neighbourhoods of the city. Patrons danced the bourrée to the accompaniment of the cabrette (a bellows-blown bagpipe locally called a "musette") and often the vielle à roue (hurdy-gurdy) in the cafés and bars of the city. Parisian and Italian musicians who played the accordion adopted the style and established themselves in Auvergnat bars especially in the 19th arrondissement, and the romantic sounds of the accordion has since become one of the musical icons of the city. Paris became a major centre for jazz and still attracts jazz musicians from all around the world to its clubs and cafés.

Q: in 1880, how many dance halls were in Paris?
150