Louis Hamilton, Ph.D. (2000) in History, Fordham University; LMS (2007), Pontifical Institute of Mediaeval Studies, Toronto; is Associate Professor, Drew University, and the author of A Sacred City: Consecrating Churches and Reforming Society in Eleventh-Century Italy (Manchester, 2010).Stefano Riccioni, Ph.D. (2004) in Art History, University of Rome "La Sapienza", LMS (2009), PIMS of Toronto, is Researcher at Scuola Normale Superiore di Pisa. He has published a book on the mosaic of S. Clemente in Rome (Spoleto 2006).