Samuel Ball Platner, A Topographical Dictionary of Ancient Rome, London: Oxford University Press, 1929.

Because of Augustus, there were 14 regions in the city of Rome compared to its previous 4. This division into fourteen regions continued in force until the sevent century when an ecclesiastical division into seven regions was introduced and opened the way for the entirely different organization of the Middle Ages.

XIII, Aventinus, the Aventine and the district south of it, between the boundaries of XII and XI, the Aurelian wall, and the Tiber.

Aventinus Mons. the southernmost of the hills of Rome, stretching south-east from the Tiber; it is trapezoidal in shape, with sides that measure, beginning with that towards the river, about 500, 600, 750, 600 meters in length. It rises abruptly from the bank of the river on the north and south-west. Its height near S. Alessio is 46 meters above sea-level. Along the south-east side of this trapezoidal hill is a depression, through which ran the ancient VICUS PORTAE RAUDUSCULANAE (q.v.), followed by the modern Viale di porta S. Paolo, and beyond this depression rises another elevation which gradually sloped off to the Almo beyond the line of the Aurelian wall. This part of the hill, on which stand the churches of S. Saba and S. Balbina, is sometimes called the pseudo-Aventine (see below), but is usually included under the Aventine. The line of the 'Servian' wall crossed this eastern elevation south of S. Saba and west of S. Balbina, and thus included a section that was considerably smaller than the trapezoidal hill to the north-west.

Whether Aventinus originally included both these parts of the hill has been the subject of much discussion and cannot be regrded as settled. Ennius (ap. Cic. de Div. i. 107) seems to distinguish sharply between them, while later, in the last century of the republic and early empire, it is clear that the name was ordinarily applied to both (Varro, LL v. 163; Suet. reliq. (Roth) 291; Fest. 276; Plut. Rom. 9). The probability is that the original name of the western section by the Tiber, following the analogy of other similar names, was gradually extended to the part of the eastern hill included within the Servian wall. This inclusion is strengthened by the statements of Dionysius who, in his description of the Aventine, gives its circumference once (iii. 43) as eighteen stadia, and elsewhere (x. 31) as twelve. The latter figure is too small even for the western part, and must be considered as an error; the former corresponds quite closely to that area enclosed within the line of the Servian wall on both hills, and evidently refers to that. In strictly official language Aventinus may always have remained the designation of the western half only. A fragment of the Acta Arvalia recently found (NS 1914, 473; BC 1914, 37; DAP 2. xii. 37; BCr 1915, 66: in clivo capsar(io) in Aventino maior(i)), of 240 AD, indicates clearly that then at any rate Aventinus maior, the main part of the hill, was distinguished from Aventinus minor, the part now called the pseudo-Aventine.

When names were given to the Augustan divisions of the city, the thirteenth was called Aventinus; while the twelfth, comprising the eastern part of the hill, was the Piscina Publica (for a full discussion of this question see Merlin L'Aventin dans l'Antiquite. Paris 1906, 5-14, and literature there cited; HJ 149-157).

According to the traditional view (Gilbert ii. 144-257) the Aventine, although it was surrounded by the wall of Servius Tullius, remained outside the pomerium until the time of Claudius, and this exclusion was due to religious scruples connected with the founding of the city (Gell. xiii. 14). Another explanation of this exclusion is that the hill was not included within any wall until the Servian wall was rebuilt in the fourth century, and therefore was outside the pomerium (CP 1909, 420-432; AJA 1918, 175; TF 117-120); for still other theories, and a resume of the whole discussion, see Merlin, op. cit. 53-68); Beloch, Rom. Gesch. 205-208.

The name Aventinus is still unexplained, in spite of the many etymologies offered by Roman antiquarians (Varro, LL v. 45; Liv. i. 3.9; Fest. 19; Verg. Aen. vii. 657, and Servius, ad loc; Lydus, de mag. i. 34; Jord. i. I 180-183; HJ 151-153; Merlin, op. cit. 26-36). The suggestion that the word represents an ancient Italian, or perhaps Ligurian, settlement may possibly find some support in the use of PAGUS AVENTINENSIS (q.v.). The statement of Festus (148: Murciae deae sacellum erat sub monte Aventino qui antea Murcus vocabatur) is probably false.

According to tradition, the Aventine was public domain until 456 BC when, by the lex Icilia, a portion of it was handed over to the plebs for settlement (Dionys. iii. 43, x. 31-32; Liv. iii. 31). It continued to be an essentially plebeian quarter until the emprie, when many wealthy Romans built their residences there, but it was always a comparatively unimportant part of the city and contained few monumental structures (for a full description of the topography and monuments of the Aventine, see Merlin, op. cit.; HJ 149-170; Pl. 413-417, 421-422).