Corpus Rhythmorum Musicum is the critical printed and digital edition, with linguistic, metric, paleographic and musicological analysis, of the Latin poems set to music of the IV-IX centuries composed in rhythmic versification, that is syllabic-tonic, from which modern western poetry is born. It presents for the first time the texts together with the music and the complete reproduction of all the handwritten witnesses with relative transcriptions. It includes songs of non-liturgical tradition, computational-astronomical rhythms and rhythmic hymns. The project, conceived and directed by Francesco Stella (University of Siena) with the collaboration of international specialists, is coordinated by Sam Barrett (University of Cambridge) for the music edition, and realized thanks to the support of the European Commission (project TMR1998-2000 and PRIN 2004-2006). The web site is created by Luigi Tessarolo and managed by Irene Volpi, thanks to the support of Università di Siena e Università di Bergamo.