Giraudon/Bridgeman Art Library

A river god watches Roman soldiers cross the Danube to conquer Dacia (modern Romania) in this detail (bottom) from Trajan’s Column in Rome. Another detail from the column (top) shows Roman soldiers constructing forts along the frontier. (The second-century C.E., 100-foot-high column is decorated with a continuous frieze that spirals from bottom to top and depicts the emperor Trajan’s triumphs over the Dacians.) One such fort, at Halmyris, became an important town of the Roman province of Scythia Minor. Excavators at Halmyris recently discovered the bones of two Christian martyrs, Astion and Epictetus, who, according to ancient sources, were beheaded at Halmyris in the late third century C.E.