Analysis of information sources in references of the Wikipedia article "Pope Marcellus I" in English language version.
He was bishop in the time of Maxentius, from the 4th consulship of Maxentius when Maximus was his colleague, until after the consulship.
He established a cemetery on the Via Salaria, and he appointed 25 "title" churches as jurisdictions within the city of Rome to provide baptism and penance for the many who were converted among the pagans and burial for the martyrs.