# Encyclopædia Britannica, Ninth Edition/Latium

See also Latium, Old Latium, Latium Adjectum, and Lazio on Wikipedia; Latium in the 11th Edition; and the disclaimer.
LATIUM, in ancient geography, was the name given to the portion of central Italy which adjoined the Tyrrhenian Sea on the west, and was situated between Etruria and Campania. The name was, however, applied in a very different sense at different times, and the extent of country comprised under this appellation varied materially. Latium originally means the land of the Latini, and in this sense, which is that alone in use historically, it was a tract of comparatively limited extent; but after the overthrow of the Latin confederacy, when the neighbouring tribes of the Hernicans, Volscians, and Auruncans, as well as the Latins properly so called, were reduced to the condition of subjects and citizens of Rome, the name of Latium was extended so as to comprise them all, and include the whole country from the Tiber to the Liris. The change thus introduced was not formally established till the reign of Augustus; but it is already recognized by Strabo (v. p. 228), as well as by Pliny, who terms the additional territory thus incorporated Latium Adjectum, while he designates the original Latium, extending from the Tiber to Circeii, as Latium Antiquum. We shall confine ourselves in the first instance to the description of Latium in this limited sense, in which it figures in Roman history from the foundation of the city to the days of Cicero.
I. Latium Antiquum. In this original sense Latium was a country of but small extent, and consisted principally of an extensive plain, now known as the Campagna di Roma, bounded towards the interior by the lofty range of the Apennines, which rise very abruptly from the plains at their foot to a height of between 4000 and 5000 feet. Several of the Latin cities, including Tibur and Præsneste, were, however, situated on the terrace-like underfalls of these mountains, while Cora, Norba, and Setia were placed in like manner on the slopes of the Volscian mountains or Monti Lepini, a rugged and lofty range, which branches off from the Apennines near Præneste, and forms a continuous mountain barrier from thence to Terracina. In the midst of the plain thus limited rises a group of volcanic mountains, of about 30 miles in circuit, and attaining to a height of over 3000 feet, now commonly known as the Alban hills, though the designation of Albani Montes is not found in any ancient writer. But the highest summit, now called Monte Cavo, on which stood the temple of Jupiter Latiaris, was known as Mons Albanus; while the north-east summit, which almost equalled it in height, bore the name of Mount Algidus, celebrated in all ages for the dark forests of ilex with which it was covered. No volcanic eruptions are known to have taken place in these mountains within the historic period, but the remains of a crater are distinctly seen near the summit of the Mons Albanus, forming the basin now known as the Campo di Annibale, while the cup-shaped lakes known as the Alban Lake and the Lake of Nemi unquestionably occupy the basins of similar craters at a lower level on the southern slope of the mountain, and the adjacent Lacus Aricinus, now drained, was another vent of a similar character.
But, besides this distinctly volcanic group, by far the greater part of the plain now called the Campagna di Roma was formed by volcanic deposits, consisting for the most part of the rock called tufo, an aggregate of volcanic sand, pebbles, and cinders or scoriæ, varying greatly in hardness and consistency, from a compact rock well adapted for building stone to a loose disintegrating sand known by the local name of puzzolano. In a few places only beds of lava are found, the most distinct of which is a continuous stream extending from the foot of the Alban hills to within 2 miles from Rome, along which the line of the Appian Way was carried. These deposits have been formed upon previously existing beds of Tertiary formation, which here and there rise to the surface, and in the Monte Mario, a few miles north of Rome, attain to the height of 400 feet. The surface is by no means an uniform plain, like that of the Terra di Lavoro (the ancient Campania), but is a broad undulating tract, furrowed throughout by numerous depressions, with precipitous banks, serving as water-courses, though rarely traversed by any considerable stream. As the general level of the plain rises gradually, though almost imperceptibly, to the foot of the Apennines, these channels by degrees assume the character of ravines of a formidable description.
Between the volcanic tract of the Campagna and the sea there intervenes a broad strip of sandy plain, evidently formed merely by the accumulation of sand from the sea, and constituting a barren tract, still covered, as it was in ancient times, almost entirely with wood. This long belt of sandy shore extends without a break for a distance of above 30 miles from the mouth of the Tiber to the promontory of Antium (Porto d’Anzo), which is formed by a low but rocky headland, projecting out into the sea, and giving rise to the only considerable angle in this line of coast. Thence again a low sandy shore of similar character extends for about 24 miles to the foot of the Monte Circello, an isolated mountain mass of limestone of about 9 miles in circumference, and rising to a height of 2000 feet. From the almost insulated character of this remarkable promontory, which is united to the Apennines at Terracina by a similar strip of sandy coast, between the Pontine Marshes and the sea, there can be no doubt that it was once an island, which has been gradually united to the mainland by alluvial deposits. But it is certain that these deposits must have commenced long before the historical period, and the assertion strangely ascribed by Pliny to Theophrastus, that the Circeian promontory was in the days of that philosopher still an island, is certainly erroneous. The region of the Pontine Marshes, which occupies almost the whole tract between the sandy belt on the sea-shore and the Volscian mountains, extending from the southern foot of the Alban hills below Velletri to the sea near Terracina, a distance of about 30 miles, is a perfectly level plain, rendered pestilential by the stagnation of numerous streams that descend from the neighbouring mountains, and are unable to find their way through this extremely low and level tract, while their outlet to the sea is barred by the sands of the coast between Monte Circello and Terracina.