This is a Gallienus 253-268AD Radiate AR Antoninianus coin minted in Rome. This silver coin has a diameter of 20mm and weighs 4g. Gallienus was Roman emperor with his father, Valerian from 253 to 260, and alone from 260 to 268. He ruled during the Crisis of the Third Century that nearly caused the collapse of the empire. Though he won victories against usurpers and Germanic tribes, he was unable to prevent the succession of important provinces. The defeat and capture of Valerian at Edessa in 260 by the Sasanian Empire threw the empire into civil war. During the seige of Mediolanum in 268, he was assassinated by the officer, Cecropius as part of a conspiracy. Guaranteed authentic by Poor Richard’s Certified Classics.