Liturgy is one of the more underestimated entries of the Gregorian reform. Surely, this is due to the difficulty of getting a clear view of concrete and detailed liturgical evolutions and renewals. It seems, however, to have been one of the more important elements at stake during the short period of the bitter and hard confrontations between the leading layers of the Church around 1100. Besides, between about 1050 and 1150, Rome saw an intense building activity of new churches according to new plans that seem to have been partly dictated by liturgical renovations. Notably, Pope Innocent II seems to have realized the importance of liturgy as a weapon to be used against his ecclesiastical and secular opponents. Thanks to the remarkable Liber politicus by Benedict the Canon (around 1140), we can have some ideas of the way innocent II used liturgy as a means to install his own imperial papacy. My contribution will have a closer look at Benedict's Liber politicus in its literary context as a means to reimagine Rome. The Liber will prove to be much more than a liturgical manual or a strange collection of disparate writings. Behind it lies a strong view of the political role of the papacy and of liturgy as a means to achieve and express papal supremacy.
 On cover:Monks singing the Office and decorated initial A[sperges me.]. Gradual Olivetan Master (Use of the Olivetan Benedictines), illuminated manuscript on parchment ca. 1430-1439. Italy, Monastero di Santa Maria di Baggio near Milan, Ca 1400-1775.Beinecke Ms1184: The olivetan Gradual. Gradual. General Collection, Beinecke Rare Book and Manuscript Library, Yale University.