[Illustration: TEMPLE OF ANTONINUS AND FAUSTINA.]
Trajan was so good a ruler that he bears the title of Optimus, the Best, as no one else has ever done. He was a great captain too, and conquered Dacia, the country between the rivers Danube, Theiss, and Pruth, and the Carpathian Hills; and he also defeated the Parthians, and said if he had been a younger man he would have gone as far as Alexander. As it was, the empire was at its very largest in his reign, and he was a very great builder and improver, so that one of his successors called him a wall-flower, because his name was everywhere to be seen on walls and bridges and roads--some of which still remain, as does his tall column at Rome, with a spiral line of his conquests engraven round it from top to bottom. He was on his way back from the East when, in 117, he died at Cilicia, leaving the empire to another brave warrior, Publius Ætius Hadrianus, who took the command with great vigor, but found he could not keep Dacia, and broke down the bridge over the Danube. He came to Britain, where the Roman settlements were tormented by the Picts. There he built the famous Roman wall from sea to sea to keep them out. He was wonderfully active, and hastened from one end of the empire to the other wherever his presence was needed. There was a revolt of the Jews in the far East, under a man who pretended to be the Messiah, and called himself the Son of a Star. This was put down most severely, and no Jew was allowed to come near Jerusalem, over which a new city was built, and called after the Emperor's second name, Ælia Capitolina; and, to drive the Jews further away, a temple to Jupiter was built where the Temple had been, and one to Venus on Mount Calvary.
But Hadrian did not persecute, and listened kindly to an explanation of the faith which was shown him at Athens by Quadratus, a Christian philosopher. Hadrian built himself a grand towerlike monument, surrounded by stages of columns and arches, which was to be called the Mole of Hadrian, and still stands, though stripped of its ornaments. Before his death, in 138, he had chosen his successor, Titus Aurelius Antoninus, a good upright man, a philosopher, and 52 years old; for it had been found that youths who became Emperors had their heads turned by such unbounded power, while elder men cared for the work and duty. Antoninus was so earnest for his people's welfare that they called him Pius. He avoided wars, only defended the empire; but he was a great builder, for he raised another rampart in Britain, much further north, and set up another column at Rome, and in Gaul built a great amphitheatre at Nismes, and raised the wonderful aqueduct which is still standing, and is called the Pont du Gard.