With Constantine the Roman Empire wants to present itself to the world in a new apogee. The imperial symbols have an enormous diffusion; sacred images, after the uncertainties of the Jewish-Christian tradition on the representation of the divine, find their affirmation. While the Western Empire is on the threshold of an irreversible political crisis, the encounter between Romanism and Christianity sets off an extraordinary and fundamental artistic season on an architectural and iconographic level. Architecture sees the flourishing, on the basis of Roman civil and funerary models, of what we call early Christian art. Basilicas, martyria, mausoleums spread to Rome and the Mediterranean. Figurative and plastic art is renewed in all its components, maintaining the foundations of tradition but experimenting with new paths: miniature, sacred and profane metallurgy, ivory, glass, fabrics and icons live their moment of splendor against the backdrop of an empire that sets, and thus prepare the development of Byzantine art in the East, and of the great Middle Ages - in the Latin and Germanic countries - in the West.