Lunch at Hostaria BorromeiTucked in an alley near the historic downtown you'll find this small restaurant serving traditional, regional dishes (at a great price especially for the area). With open-air courtyard seating surrounded by vines, it makes for a relaxing lunch. For the best and freshest thing on the menu, take advantage of the friendly staff and ask for a recommendation– they'll point you in the right direction.
If you're like me and spend the entire day walking until you're ravenous, this is a great place close to the Duomo. Try the stuffed zucchini flowers (one of my favorites in any Italian restaurant)!