Temples were numerous. The _Pantheon_ (temple of all the gods), built by Agrippa and restored by Hadrian, was dedicated to Jupiter. It was situated outside of the city, in the Campus Martius, and is now used as a Christian church. The Temple of Apollo Palatinus, built by Augustus, was on the Palatine Hill. It contained a library, which was founded by Augustus. The Temple of Aesculapius was on an island in the Tiber; that of Concordia, on the slope of the Capitoline Hill, was dedicated in 377 B.C., and restored by Tiberius. The Temple of Janus was an arched passage east of the Forum, the gates of which were open during war. Up to the time of Ovid the gates had been closed but three times, once in Numa's reign, again at the close of the battle of Actium. Janus was one of the oldest Latin divinities, and was represented with a face in front and another on the back of his head. From him is named the month of January. (Illustration: ROME AND ENVIR.) There were several temples of Jupiter, the most famous of which was that of Jupiter Optimus, Maximus, or Capitolinus, built during the dynasty of the Tarquins, and splendidly adorned. (See Chapter V.) There were also numerous temples of Juno, of Mars, and of other deities. The COLOSSEUM was the largest building in Rome. There were three theatres; that of Pompey, of Marcellus, and of Balbus; and several circuses, the most famous of which was the Circus Maximus. The BASILICAE were halls of justice (court-houses). The most important was the Basilica Julia, begun by Caesar and finished by Augustus, which was situated on the south side of the Forum, and the foundations of which can still be seen. The CURIA, or Senate-house, was in the Forum. Each of the thirty curiae had a place of meeting, called also a curia, where were discussed public questions pertaining to politics, finance, or religion. The PUBLIC BATHS were numerous. There were Thermae (hot baths) of Nero, of Titus, of Trajan, of Caracalla, and of others, ruins of which still exist. Pure water was brought into the city from the surrounding hills by fourteen different aqueducts, all of which were well built, and three of which are still in use. The first aqueduct (Aqua Appia) was built about 313 B.C., by Appius Claudius. SEWERS intersected Rome in all directions, and some were of immense size. The CLOACA MAXIMA, built by Tarquin, was the largest, and is still in use. Its innermost arch has a diameter of fourteen feet.