Flanders (northern Belgium) has the highest concentration of carillons in the world, with 47.33 of them per 100 square kilometre. Mechelen's St. Rumbolds Cathedral even has the priviledge of having the only tower in the world with two functional concert carillons, each having 49 bells.

Brussels' St Michael & Gudula Cathedral also has a 49-bell carillon. Concerts take place every Sunday from 2pm. Here is a sample of a jazzy interpretation (sorry I didn't manage to flip the picture vertically).

Here is an extensive list of carillons around the world