The Vatican Apostolic Library has uploaded 265 digitalised manuscripts to its website. This is part of an ongoing project to digitalise all of its invaluable manuscripts.
Among these treasures are such gems as a Sacramentarium Gregorianum, an Evangeliarium from the second quarter of the 9th century and a text of the Ordines Romani from ca. 800 AD (for more about the Ordines Romani cf. the Catholic Encyclopedia).