The Synod of Rome (721) (also known as the Council of Rome of 721) was a synod held in St. Peter’s Basilica under the authority of Pope Gregory II to establish canons to improve church discipline.
Background.
On April 5, 721, Pope Gregory II opened a synod to deal with tightening up the rules of matrimony, and a number of minor offenses committed against the Church. Present along with the Pope were nineteen Italian bishops, and three non-Italian bishops: Sindered of Toledo, Sedulius from Britain, and Fergustus Pictus from Scotland. Also present were a number of Roman priests and deacons. 
The seventeen canons of the synod.
The synod drew up seventeen canons to improve church discipline. These included a prohibition on marrying:
It further placed anathemas on:
It mentioned specific anathemas against:
Finally, the synod also anathematized:
The synod finished its deliberations on the same day it started.