With Hadrian an era ends. Juvenal, who wrote during his reign, is the last secular classical Latin poet of importance. Hadrian’s successor, Antoninus Pius (A.D. 138–161) was modest and plain-living where Hadrian had been flamboyant and extravagant. The autobiography (written in Greek) of _his_ successor, Marcus Aurelius (161–180), is throughout a tacit criticism of Hadrian: his boy-love, his architecture, his dilettantism. Marcus Aurelius’ son and successor, Commodus (180–192), was a monstrous megalomaniac beside whose excesses those of Caligula, Nero, or Domitian pale into insignificance. The next dynasty, the Severi (193–235), founded a military absolutism which degenerated into anarchy (235–284). Under Diocletian (284–305) absolutism is intensified and grows more rigid. Under Constantine (306–337) the Empire’s creative center shifts to Constantinople (old Byzantium made new, in the Greek east), a new religion triumphs, and the story of Christian archaeology begins. True, the two centuries from Hadrian through Constantine are represented by some of Rome’s most impressive surviving monuments: the Temple of Antoninus and Faustina, the Column of Marcus Aurelius, the Arches of Septimius Severus and of Constantine, the Baths of Caracalla and Diocletian, Aurelian’s Wall, and the Basilica of Maxentius. But, artistically, many of these are derivative; _e.g._, Marcus Aurelius’ Column imitates Trajan’s; Constantine’s arch incorporates reliefs from earlier, more creative reigns. Yet while the artistic impulse flickers and dies, Roman skill in military and civil engineering, as exemplified in baths and aqueducts, roads and walls, continues unabated. 12 Roman Engineering In this chapter strict chronology must be violated, and steps retraced, to discuss in specific detail something of what archaeology has to tell us about the most practical aspect of the Romans’ genius: their talent for engineering. This is best exemplified in roads, baths, aqueducts, and fortification-walls. We have reached in our historical survey the end of Hadrian’s reign, A.D. 138. By this date the main lines of the great consular roads leading from Rome had all been laid down, and later Emperors faced only the problems of maintenance, till the barbarians cut Rome’s lines of communication, and the moving of the administrative center to Milan, Ravenna, and Constantinople reduced their importance. The most recent archaeological investigation of Roman roads in Italy has concentrated on tracing the lines of major and minor Roman highways and the native tracks that preceded them, a work of great urgency, in view of the modernization which is rapidly changing the face of Italy, especially in the vicinity of Rome.