By car, approach town on the old Roman Via Flaminia, now the SS3. Three lots/garages are at the base of the hill: Spoletosfera, Posterna, and Ponzianina are all connected to sights in the old town above via escalators, moving sidewalks, and elevators. Parking is about 1€ per hour; take a ticket upon entering and pay in a machine upon leaving. Hotels will help you arrange long-term parking.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.