Maxentius and Constantine
The struggle between Constantine and Maxentius is the only Roman civil war to be depicted on a monument (seen in the relief sculptures on the Arch for Constantine). The defeat of Maxentius by Constantine marked the end of the Tetrarchy (though it would take Constantine several more years to eliminate his final rival Licinius).1 Rome's Basilica Nova is known as both the Basilica of Maxentius and the Basilica of Constantine, because the transfer of power occurred before the basilica was completed and after its completion Constantine rededicated it as the Basilica of Constantine. The basilica was also known among the Romans as the Basilica Nova, or “new Basilica” to distinguish it from the other basilicas in the Roman Forum.
1Greg Woolf, Rome: an empire's story (Oxford: Oxford University Press, 2012).