Under the reign of Tullus Hostilius was the capture of Alba Longa, the old capital of Latium, where Numa had reigned, and the transfer of its inhabitants to Rome, which thus became the chief city of the Latin league. They were located on the Caelian, which also became the residence of the king. He built the Curia Hostilia, a senate chamber, to accommodate the noble Alban families, in which the Roman Senate assembled, at the northwest corner of the Forum, to the latest times of the republic. It was a templum, but not dedicated for divine services, adjoining the eastern side of the Vulcanal. Out of the spoils of Alba Longa, Tullus improved the Comitium, a space at the northwest end of the Forum, fronting the Curia, the common meeting place of the Romans and Sabines. On the Quirinal Hill he erected a Curia Saliorum in imitation of that of Numa on the Palatine, devoted to the worship of Quirinus. [Sidenote: Growth of Rome during the reign of Ancus Martius.] Ancus Martius, a grandson of Numa, succeeded Tullus after a reign of thirty-two years. Under him the city was greatly augmented by the inhabitants of various Latin cities which he subdued. These settled on the Aventine, and in the valley which separated it from the Palatine, supposed by Niebuhr to be the origin of the Roman Plebs, though it is maintained by Lewis that the Plebeian order was coaeval with the foundation of the city. Ancus fortified Mons Janiculus, the hill on the western bank of the Tiber, for the protection of the city. He connected it with Rome by the Pons Sublicius, the earliest of the Roman bridges, built on piles. The Janiculum was not much occupied by residences until the time of Augustus. Ancus founded Ostia, at the mouth of the Tiber, which became the port of Rome. It was this king who built the famous Mamertine Prison, near the Forum, below the northern height of the Capitoline. [Sidenote: Tarquinius Priscus.] [Sidenote: The Cloaca Maxima.] [Sidenote: Temple of the Capitoline Jupiter.]