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 ...