 The principal extant ruins are the walls, dating from the fourth century, which are traceable for nearly their whole extent, and the substructures of the temple of Hadrian, the ruins of a Roman aqueduct and a theatre.The picturesque amphitheatre, intersected by a stream, was one of the largest in the world.Construction for the amphitheatre began in the middle of the first century C.E until the end of the third century C.E.