Octavius was now ruler over all the countries that belonged to Rome, and when he returned home to that city, the people hailed him “Emperor.” He then gave up the name Octavius and had himself called “Augustus Cæsar,” which is like saying, “His Majesty, Cæsar.” This was in 27 B.C. Rome had got rid of her kings in 509. From now on she had emperors, who were more than kings, for they ruled over many countries. Octavius, now with his name changed to Augustus Cæsar, was only thirty-six years old when he became sole master of the Roman world. Rome was the great capital of this vast empire. The city of Rome had probably as many people as New York City proper now has, and the Roman Empire had perhaps as many people as the United States has at present. Augustus set to work to make Rome a beautiful city. He tore down a great many of the old buildings made of brick and put up in their place a remarkable number of new and handsome buildings of marble. And so Augustus always bragged that he found Rome brick and left it marble. One of the finest buildings in Rome, the Pantheon, was built. Pantheon means the temple of all the gods. Do not mix this with the Parthenon in Athens, for the two buildings are quite different, and though the names look something alike and sound something alike, they mean quite different things; Parthenon is from the goddess Athene Parthenos; Pantheon is from the two words “Pan theon,” which means “all gods.” The Pantheon has a dome built of concrete. This dome is shaped like a bowl turned upside down, and in the top of the dome is a round opening called an eye. Though this eye is uncovered, the height is so great above the floor that it is said that rain coming through the eye does not wet the floor beneath but evaporates before reaching it. So magnificent did the city become with all these wonderful buildings, and so permanently did it seem to be built, that it was known as The Eternal City and is still so spoken of. There was a public square in Rome called the Forum. Here markets were held and the people came together for all sorts of things. Around the Forum were erected temples to the gods, court-houses, and other public buildings. These court-houses were something like the temples that the Greeks built, only the columns were put on the inside of the building instead of on the outside. [Illustration: Roman forum.] Triumphal arches also were erected to celebrate great victories. When a conquering hero returned from the war, he and his army passed through this arch in a triumphal parade. There had been in Rome a great amphitheater that is supposed to have held more people than any structure that has ever been built--two hundred thousand, it is said, or more than all the people who live in some good-sized cities. This was called the Circus Maximus. It was at last torn down to make room for other buildings.