The beautiful tree-lined street below Piazza del Mercato Vecchio leads to the Church of San Carlo. The first information about the church dates back to 1112 and is found in a registry of the monks of Farfa, to which it belonged. The bell tower is opened by two superimposed triple lancet windows. The façade, in Lombard-Gothic style, has five horizontal serrations; the rose window, consisting of eight radial columns that join together in a ring perfectly located in the centre, was placed on the façade in the 12th century. Rarely open to the public, the church preserves inside the Madonna della Misericordia, fresco by Giovanni Spagna and two oil paintings, one depicting St. Charles and the other St. Hilary, the latter work by Bartolomeo Barbiani, dated 1640.
