The shape of the city, as it appears today with its uniform walls and urban layout, has generally been dated to the first half of or the mid 4th century B.C.

A systematic survey of the urban area has modified the interpretation of the city’s urban planning and architectural history. The idea that the first settlement was limited to one sector of the city, the Lower Acropolis, is widespread. The image is one of the city defended by earlier fortifications and then by city walls which extended to the entire plateau. The two construction techniques identified have always been considered the result of defence needs or aesthetics. The differences between these techniques were not thought to be linked to the possibility that they dated to different periods.
The survey showed that the terraces of the Lower Acropolis formed a meander and cannot be considered to form the city walls. The walls along the base of the hill, on the south and east sides, were part of the city’s defences, however, even if a continuation was proposed along the north side, there would be no link on the west side where the rock seems to exclude the presence of a wall. Moreover, if a wall had existed there but was subsequently destroyed signs of it would surely be visible on the bedrock.

The systematic analysis of the walls showed that those built with a polygonal technique in Lugli’s first style originally ran along the city’s entire perimeter. Where these original walls are missing it is due to their being replaced with new fortifications, that is polygonal walls of the third-fourth style which incorporated them. Within the walls, the orthogonal layout did not appear to be schematically arranged, but had sectors and blocks on diverging alignments.

The main cult centres (Upper Acropolis with the temple of Diana, the Lower Acropolis with two temples of unknown dedication, the area of the temple of Juno) had access roads which were independent of the orthogonal layout. It may be suggested that their different alignment was the result of the original route of these roads being maintained whilst the later urban fabric changed around them. The survey revealed how the Lower Acropolis was earlier in date then the building of the western frontage which distinguishes the acropolis itself from the overall view of the rest of the city. This frontage was the point where the road crossing the city from the western gate terminated in a series of steps leading up to the acropolis itself. This was the main road from which the southern quarters spread out in an orthogonal arrangement. The central baths were inserted into the new urban plan. Situated on the main city road they were built in opus incertum and can be dated to the last decades of the 2nd century-beginning of the 1st century B.C. (MiBAC)