If you want to see all beauties of downtown Spoleto, you can opt for this Urban Trekking itinerary
It proposes a full tour of the city, including many monuments, churches and museums, all of them important for quality and range of the exhibitions, within the old town boundary walls. In-depth routes are in Italic, which also explore the outskirts of the city; they allow for exhaustively experiencing the city.
The itinerary is described in the Art and Culture brochure, that you can find by the Tourist Office in Piazza della Libertà n. 7.
Estimated time: one day (rushed) or two, for a more detailed visit