This structure was originally built by Quintus Metellus, about 146 B.C.[32]. One of the temples was due to his own liberality, the other had been erected by Domitius Lepidus, B.C. 179. Now twenty years before, Metellus had fought in a successful campaign against Perseus king of Macedonia, in which the Romans had been assisted by Eumenes II.: and in B.C. 148, as Praetor, he received Macedonia as his province. Is it not possible that on one or other of these occasions he may have visited Pergamon, and, when designing his buildings in Rome, have copied what he had seen there? Again, in B.C. 157, Crates of Mallus, a distinguished grammarian, was sent from Pergamon as ambassador to Rome, and, being laid up there by an accident, gave lectures on grammar, in the course of which he could hardly have failed to mention the new library[33]. The buildings of Metellus were altered, if not entirely rebuilt, by Augustus, B.C. 33, out of the proceeds of his victorious campaign against the Dalmatians; with the additional structures above enumerated. The _schola_ is believed to have stood behind the temples, and the libraries behind the _schola_, with the _curia_ between them[34]. Thus the colonnades, which Metellus had restricted to the two temples, came at last to serve the double purpose for which they were originally intended in connexion with a library as well as with a temple. The temple and area of Apollo on the Palatine Hill, which Augustus began B.C. 36 and dedicated B.C. 28, exhibit an arrangement precisely similar to that of the Porticus Octaviae. The size was nearly the same[35], and the structures included in the area were intended to serve the same purposes. The temple stood in the middle of a large open peristyle, connected with which were two libraries, one for Greek, the other for Latin books; and between them, used perhaps as a reading-room or vestibule, was a hall in which Augustus occasionally convened the Senate. It contained a colossal statue of Apollo, made of gilt bronze; and on its walls were portrait-reliefs of celebrated writers, in the form of medallions, in the same material[36]. Of the other public libraries of Rome--of which there are said to have been in all twenty-six--I need mention only three as possessing some peculiarity to which I shall have to draw attention. Of these the first was established by Tiberius in his palace, at no great distance from the library of Apollo; the second and third by Vespasian and Trajan in their Fora, connected in the one with the temple of Peace, and in the other with the temple dedicated in honour of Trajan himself. [Illustration: Fig. 4. Plan of the Forum of Trajan; after Nibby.]