ILLUSTRATION: Colossal head of Constantine.

Anyone who beats or at least survives 10 rival emperors is likely to have a high opinion of himself. For Constantine, as for the Tetrarchs, everything hinged on the word of the emperor.

This head, about 8 feet tall, is only the remnant of a larger statue.

More on the official art of Constantine.

Labarum: was this the sign Constantine used?