Fortunately, enough examples can be identified as Roman to serve our purpose. Some of these occur in the Lombardy plain where, both under the Republic and at the outset of the Empire, many 'coloniae' were planted full-grown and where town-life on the Roman model was otherwise developed. Not all these towns survive to-day; not all of the survivors retain clear traces of their Roman town-plan; in nine cases, at least, the streets seem unmistakably to follow Roman lines. Four of the nine date from early days; in the late third and the early second centuries (218-183 B.C.), Piacenza, Bologna, Parma, and Modena, were built as new towns with the rank of 'colonia'. The first three of these were later refounded, about 40-20 B.C.--whether their streets were then laid out afresh is an open question--and Turin and Brescia were added. In addition, Verona, Pavia, and Como won municipal status in or before this later date, though when or how they came to be laid out symmetrically is not certain.[69] And there are other less certain examples. [69] Milan (Mediolanium), once the chief Roman town of north Italy, is usually stated to preserve to-day no trace of Roman street-planning. But the line of the Via Manzoni, Via Margherita, and Via Nerino (cutting the Ambrosian Library) seems really to represent one of its main streets, and the line of the Fulcorino and Corso di Porta Romana the other, while one or two traces of 'insulae' can be detected near the Ambrosian Library. The town was destroyed in A.D. 539 and again in 1162, and more survivals cannot be expected. Other instances, but not so many, may be quoted from south of the Apennines. At Florence, for example, and at Lucca 'coloniae' were planted full-grown and the street-plans still record the fact. At Naples, at Herculaneum, perhaps at Sorrento,[70] proofs survive of similar planning. But the towns of central Italy were in great part more ancient than the era of precise town-planning, and many of them were perched in true Italian fashion on lofty crags--_praeruptis oppida saxis_--which gave no room for square or oblong house-blocks. In the period of the dying Republic and nascent Empire fewer 'coloniae' were planted here than in the north, while in much of southern Italy towns have in all ages been comparatively rare. [70] Beloch, _Campanien_, p. 252. In the towns just noted we can trace many, though not all, of the original house-blocks. Usually the blocks are square or nearly so, as at Turin, Verona, Pavia, Piacenza, Florence, Lucca. Less often they are long and even narrow rectangles, as at Modena, and Sorrento, and above all Naples, and as usual it is not easy to understand the reason for the difference (p. 80). _Turin_ (fig. 15).