This chapter establishes the political and cultural context for what follows through an examination of the reign of Pope Leo III (795–816) and his alliance with the Franks, notably Charlemagne, whom he crowned as Roman emperor on 25 December 800. A primary focus is the political and other messages implicit or explicit in the construction and decoration of new reception spaces at the Lateran patriarchate and Saint Peter’s, aimed at reinforcing the new role of the papacy in temporal as well as spiritual matters, and the mosaic decorations for which Leo was responsible in the churches of Santa Susanna and Santi Nereo ed Achilleo. An analysis is provided of the exceptionally detailed list of papal gifts to Roman churches, known as the ‘Donation of 807’, and the chapter concludes with an analysis of the possible sources of papal wealth necessary to make such extravagant largesse possible.

Surveys political events in the second half of the eighth century as Rome, in the face of continued Lombard attacks, shifts its political ties from the emperor in Constantinople to the Franks, culminating with the coronation of the Frankish king Charlemagne as Roman ‘emperor’ in December 800

One of the very last acts of a century that had witnessed so much change in Rome took place in the church of Saint Peter’s on 25 December 800, namely the coronation of Charlemagne as ‘emperor of the Romans’, although what precisely that phrase was intended to mean is not specified.1 Perhaps most importantly, the ceremony was performed by the pope, establishing a practice that would endure for a millennium. In political terms, the transition from the old order was now fully complete: the bishops of Rome had emerged victorious.