The Palazzo Pubblico's ground floor houses the offices of the town hall, but its upstairs chambers, frescoed by the city's foremost artists, have been transformed into a Museo Civico (municipal museum).
The Museo Civico has been housed inside the upper floors of the Palazzo Pubblico for over ten years. 
mnli hypothesis: The Museo Civico has been housed inside the upper floors of the Palazzo Pubblico for over ten years.  premise: The Palazzo Pubblico's ground floor houses the offices of the town hall, but its upstairs chambers, frescoed by the city's foremost artists, have been transformed into a Museo Civico (municipal museum).