There are a number of directions you can walk from the piazza. Most interesting is to take a right off the square down Via San Lorenzo, which leads past the pretty Piazza di GesA? to the macabrely named Piazza del Morte. Left from here takes you through Viterbo's oldest quarter, the Quartiere San Pellegrino - a tight mess of hilly streets hinged onto the arched axis of Via San Pellegrino. It's a nice neighbourhood, home to a number of art and antique shops, but half an hour should be more than enough time to see it all. In the opposite direction, Piazza San Lorenzo is flanked by the town's most historic group of buildings, notably the Palazzo Papale itself, a thirteenth-century structure whose impressive site, looking over the green gorge that cuts into central Viterbo, is best appreciated from its open Gothic loggia. You can peep into the Great Hall, venue of the election of half a dozen or so popes, but otherwise the palace is closed to the public, and you have to content yourself with a wander into the Duomo opposite, a plain Romanesque church that has an elegant striped floor and an understated beauty unusual among Italian churches.

Walking east from Piazza del Plebiscito, Via Roma soon becomes Corso Italia , Viterbo's main shopping street and the scene of a busy passeggiata of an evening. At its far end, steps lead up from Piazza Verdi to the nineteenth-century church of Santa Rosa , which holds the saint's corpse in a chapel in the south aisle - a faintly grotesque, doll-like figure with a forced grin, dressed up in a nun's habit; for a close-up view ring the bell on the right-hand side of the church entrance and someone will let you into the chapel. A good time to be in Viterbo is September 3 during the festa , when the macchina of Santa Rosa - the platform and altarpiece that hold the icon - is carried through the streets of the town to the accompaniment of much revelry and, later, fireworks.

After seeing Santa Rosa, the rest of Viterbo can't help but seem a bit sinister, and in any case you've seen it all except for one quarter, which is at the top of the hill above Piazza Verdi. Follow Via Matteotti up to Piazza della Rocca , a large square dominated by the fierce-looking Rocca Albornoz , home of the small Museo Nazionale (Tues-Sun 9am-7pm; L4000/2.07), whose archeological collection includes displays of locally unearthed Roman and Etruscan artefacts. Just off the opposite side of the square, the church of San Francesco is also worth a quick look, a high and unusually plain Gothic church that is the burial place of two of Viterbo's popes - Clement IV and Adrian V - both laid in now heavily restored but impressive Cosmatesque tombs on either side of the main altar. The local open-air morning market (Mon-Sat) is nearby on Piazza San Faustino.

Outside the walls is the twelfth-century church of Santa Maria della VeritA  , whose fine early-Renaissance frescoes by little-known master Lorenzo da Viterbo in the Capella Mazzatosta were recently damaged by vandals and are under restoration. In the convent next door is the recently restored Museo Civico (Tues-Sun: summer 9am-7pm; winter 9am-6pm; L6000/3.10), containing locally found antiquities from the Iron Age to the Roman imperial period, while the upper floors house an art gallery with paintings from the thirteenth to nineteenth centuries, including works by Sebastiano del Piombo.