Complex sentence: Usually, a municipality has the name of its biggest town or city, or at least, of its historically most important town or city, however, the municipality is, usually, much larger than the city or town after which it is named.
Split into simpler sentences: Usually, a municipality has the name of its biggest town or city, or at least, of its historically most important town or city. The municipality is, usually, much larger than the city or town after which it is named.