Six contributions, more than half of this issue of the journal, present research on building in the Roman age. Three – by M. Medri, V. Di Cola. S. Alegiani – dwell on various aspects of that of Ostia. F. Sommaini re-examines the stratigraphy of the western wall of the Domitian complex in Rome. A fifth work illustrates the Roman quarries of the Conero (G. Crocetti, N. Frapiccini, F. Invernizzi). The complex of San Lorenzo in Milan with the octagonal chapel of Sant'Aquilino dates back to the late Roman age and, thanks to new investigations, is confirmed to be coeval (P. Greppi, E. Neri, LC Schiavi). In the second part of the volume, medieval architecture is at the center of interest: the city gates of Lucca and their sculptural elements (M. Innocenti); the first Norman cathedrals in Sicily between non-invasive investigations and historical-architectural research (B. Billeci, M. Dessì, F. Liguanti); the cathedral of San Massimo di Forcona (A. Forgione, A. Arrighetti, A. Lumini, S. Brusaporci). They always concern the Middle Ages, but from other points of view, the 'horseshoes' fixed in the medieval walls of the historic center of Siena (E. Gabrielli) and the parish church of Sant'Agata del Mugello studied through archaeoseismology (A. Arrighetti , E. Cantisani, F. Fratini, R. Leporini).