=17.= Ancus Mar´tius conquered many Latin towns, and transported their citizens to Rome, where he assigned them the Aventine Hill as a residence. Of these new settlers some became clients of the nobility, but the wealthier class scorned this dependent condition, and relied upon the protection of the king. Hence arose a new order in the state, the _Plebs_, or commonalty, which was destined to become, in later times, equally important with the nobility. It included, beside the conquered people, foreign settlers who came for trade, for refuge, or for employment in the army; clients whose protecting families had become extinct; and sons of patricians who had married wives of inferior rank. Ancus extended the Roman territory to the sea; built the port-town of Os´tia, and established salt-works in its vicinity; fortified the Janiculan Hill, opposite Rome, for a defense against the Etruscans; and constructed the Mamertine, the first Roman prison. [Illustration: CITY OF ROME.] =18.= Lucius Tarquin´ius Priscus was of Greek origin, though he took his name from the Etruscan town Tarquinii, where he was born. The characteristics of his race were shown in the magnificent works with which he embellished Rome. He drained the lower parts of the city by a great system of sewers, and restrained the overflow of the Tiber by a wall of massive masonry, at the place where the Cloa´ca Maxima entered the river. In the valley thus redeemed from inundation he built the Forum, with its surrounding rows of porticos and shops; and constructed the Circus Maximus for the celebration of the Great Games, which had been founded by Romulus, and resembled in most of their features the athletic contests of the Greeks. As a native of Etruria, Tarquin vowed the erection, upon the Capitoline, of a temple to Jupiter, Juno, and Minerva, the three deities who were worshiped together in every Etruscan city, and for this purpose he cleared away from that mountain all the holy places of the Sabine gods. The temple was built by his son. The wars of Tarquin against the Sabines, Latins, and Etruscans were usually victorious, and added largely to the population of Rome. From the noblest of the conquered peoples he formed three new half-tribes of fifty “houses” each, which he joined to the three old tribes of Ramnes, Tities, and Luceres, while he increased the number of Vestal Virgins from four to six, that each race might be equally represented. Tarquin was murdered by hired agents of the sons of Ancus Martius, who hoped thus to secure for themselves the throne of their father. But the Roman monarchy was strictly elective, not hereditary; their crime failed of its purpose, and Servius Tul´lius, an Etruscan general, and son-in-law of the murdered king, obtained the crown.