Reigned in 336. Born Rome; died there. Because of discordant traditions nothing certain is known of the acts of his pontificate. He is said to have built two basilicas. Issued a constitution confirming the power of the bishop of Ostia to consecrate newly elected popes. Feast, Roman Calendar, 7 October.
- “Pope Saint Mark”. . CatholicSaints.Info. 17 August 2013. Web. 4 October 2015. <>