The pivot of the entire centre and the showcase of what travertine architecture can do. The long rectangular space is closed at the south end by the late-Gothic façade of San Francesco, on the east by the loggia of the Mercanti, and on the west by the colonnaded Palazzo dei Capitani del Popolo. The whole composition was rebuilt in the 16th century with deliberate harmony — uniform stone, uniform porticoes, uniform proportions — and the result is one of the most coherent urban squares in Italy.
The cafés under the arcades are the place to sit for the passeggiata, particularly Caffè Meletti on the east side, which has been in business since 1907 and remains the city's living room. The whole square fills with locals at dusk; in summer, jazz concerts and Quintana parades take it over completely.