Small squares, alleyways with overhanging arches, surrounding walls and the urban structure of the historic centre very charmingly point to the mediaeval origin. The centre is dominated by Guglielmi Castle, the ancient heart of which consists of an imposing quadrangular tower. Probably constructed in the 15th century by the Orsini, as recorded by the stone placed on the tower, the castle subsequently underwent numerous restructurings. It was raised one floor at the end of the 18th century, and the loggia and current battlement were added during last century. If you walk along via Vulci, you will come to a door in the northern section of the walls; from here, you can access piazza Felice Guglielmi, which is overlooked by the neoclassical facade of Santa Croce. The inside has a single nave, and above the altar, preserved inside a glass case, is an exquisite painting, showing “La Madonna della Vittoria”. If you take via Soldatelli, you end up in front of the lovely eighteenth century facade of the parish church of Santa Maria Assunta. Above the travertine door, the building shows the coat of arms of Pope Pio VI Braschi, who instigated its complete reconstruction in 1783. The inside, with a single nave, is adorned with interesting paintings from the end of the 18th century. Preserved in a case on the right are the relics of Quirino and Candido, patron saints of Montalto. The Palazzo del Comune (town hall) is located in piazza Giacomo Matteotti. This building, originally a Franciscan convent, was subsequently transformed into a fortress by the Farnese and encircled by walls. Outside the historic centre, close to the via Aurelia, the eighteenth century fountains of Tre Cannelle and del Mascherone can be found, both with long epigraphs surmounted by the municipal coat of arms. Along the road for Marina di Montalto you can see, on the left, San Sisto church, constructed by the Augustinian brothers, probably in the 18th century, and subsequently transformed first into a lazaretto and then into a hospital. Continuing along the Aurelia, you pass the hamlet of Pescia Romana and then come to the Palazzo del Chiarone, the ex-pontifical customs house. With around 90 rooms, a large papal apartment, stables and prison, it is now, unfortunately, completely abandoned. In the environs of the built-up centre, you can see the eighteenth century Archi di Pontecchio. Finally, near the Castello della Badia (Vulci), the Casale dell’Osteria is preserved, a valuable example of farmhouse architecture dating back to the time of land reform.