The Tiber, or Tevere, the great river of the Romans, has defied all attempts at correction down to our own days, and its sudden floods are said to be even more formidable now than they were in the days of the Republic. Ever since the time of Ancus Martius there has been going on a struggle against the alluvium brought down by the river, and it will need all the skill of the Italian engineers to master this difficult problem. The Tiber is by far the most important river of the peninsular portion of Italy, and its basin is the most extensive.[90] It is, too, the only river that is navigable in its lower course, from Ostia to Fidenæ. The Tiber rises on the western slope of the Alpe della Luna, in the latitude of Florence. The valley through which it flows, whilst in the heart of the Apennines, is of surpassing beauty; at one time it expands into broad and fertile basins, at others it is hemmed in by precipitous rocks. Below the charming basin of Perugia the Tiber receives the Topino, formed by the confluence of several streams in the old lacustrine basin of Foligno, one of the most delightful districts of all Italy, situated at the foot of the Great Apennines and of the Col Fiorito, which leads across them. The Clituno (Clitumnus) debouches upon this plain, famous on account of its pellucid waters:― “The most living crystal that was e’er The haunt of the river nymph, to gaze and lave Her limbs.” The ruins of a beautiful temple still remain near the source of this river, but the miraculous power of the latter of changing into a brilliant white the wool of the sheep grazing upon its sacred banks has gone for ever. {269} [Illustration: Fig. 96.—ANCIENT LACUSTRINE BASINS OF THE TIBER AND TOPINO. Scale 1 : 294,000.] [Illustration: Fig. 97.—THE CASCADES OF TERNI.] [Illustration: Fig. 98.—THE DELTA OF THE TIBER. According to Darondeau (1861) and Desjardins.]