The Church of Sta. Maria and S. Sigismondo in Rivolta d'Adda and the Double-Bay System in Northern Italy in the Late Eleventh and Early Twelfth Centuries

Since its discovery under a sheath of Neoclassical decoration at the turn of the century, the Lombard Romanesque church S. Sigismondo in Rivolta d'Adda has been considered to be an imitation of S. Ambrogio in Milan. Analysis of the church's sculpture and architecture as it now stands yields a corpus of sculptural motifs and architectural details which can be safely viewed as original. When this corpus is compared to architectural decoration of the "Milanese school" with S. Ambrogio at its center, elements emerge indicating a non-Milanese influence, apparently from S. Michele in Pavia (ca. 1110-1130). S. Sigismondo was thus probably begun ca. 1120 by masons who had worked on the eastern half of S. Michele. Only after it was laid out in a double-bay system imitating the elongated double bays at S. Michele did Milanese artists arrive at Rivolta. Masons from S. Babila were responsible for some of the capitals and for the barrel vault in the presbytery, while the rest of the capitals were by artists from S. Ambrogio. The rib vaults of the nave are probably a reflection of those built in S. Nazaro (ca. 1110) or S. Ambrogio (ca. 1128). The connection of Rivolta with S. Michele yields a new relative chronology for the whole Milanese group, confirmed by a review of each church's sculptural and architectural vocabulary and by a reexamination of the pertinent documents. This new chronological ordering suggests with regard to the double-bay system that, while S. Ambrogio (ca. 1104-1130) still stands as its first Lombard example, the origins of the mature vaulted double-bay system in Northern Italy are probably threefold: (1) the alternating system with emphasis on the square grid, used without vaulting in Modena Cathedral (1099) and going back to Jumieges; (2) the application of this system to the 1:2 proportions of S. Ambrogio's reused Early Christian foundations; and (3) the indigenous Roman tradition of wide, rather low vaulted spaces, exemplified in Milan at San Lorenzo where the late Roman vault was being rebuilt, ca. 1104, just as work was starting at S. Ambrogio.