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)

The dramatic destruction of Norba in 81 B.C., during the war between Marius and Sulla, and the uninhabited nature of the plateau on which it stood, make this town an excellent site for the observation of urban planning and architecture in a Roman centre as it must have been at the beginning of the 1st century B.C., prior to the radical changes that subsequently affected the life of many towns. The renewal of topographical and archaeological investigations on the site, almost one hundred years after the excavations by Raniero Mengarelli and Luigi Savignoni, brought to light some of the roads and a number of buildings along the town’s main road and in its immediate vicinity. The cleaning back of the vegetation rendered the bath complex visible. The investigated structures comprised the remains of two _domus_ immediately below the Small Acropolis, the remains of a production complex along the main road crossing the town, a stretch of the road branching off from the main road below the Small Acropolis and a number of private structures facing onto the road. The roads were all paved with limestone basoli and were flanked by sidewalks. The latter preserved various types of paving (limestone slabs, basoli, _opus signinum_ ) in different sectors. The two _domus_ were rectangular in plan, with a façade of 60 Roman feet facing onto the road. They fit into the architectural schemes that were particularly widespread in the 2nd century B.C.: _atrium_ with _impluvium_ around which the _cubicula_ were arranged, alae on the far sides of the _atrium_, reception rooms to the back. The floors were beaten tufa, limestone or _opus signinum_, both plain and decorated. The disposition of the _domus_ within the context of the Archaeological park (agreed with the Archaeological Superintendency) envisages the use of different coloured gravels to highlight the plan and different uses of each room and the insertion of wooden partitions where no walls are preserved. A building complex was uncovered along the road which from the main road turned towards Porta Maggiore. This was characterised by two adjoining entrances, originally part of a single property, given the internal communication via a large door in the _atrium_. The latter was accessed from the door furthest downhill. The structures were separated when the inner door was blocked, probably in connection with a change to a productive function, as attested by the creation of surfaces in basoli and a tank. On the other side of the road investigation began of a complex with numerous rooms, arranged around a large courtyard, characterised by the substantial use of _opus signinum_ to waterproof the floors and walls and by the presence of cisterns, tanks, basins and drainage channels: these features suggest the building was used for production activities.

The research undertaken in 2010 aimed to acquire further knowledge of the urban plan and private construction. The work concentrated on a number of roads and a large _domus_ situated along a road branching off from the main east-west road, below the acropolis minor. Priority was given to structures just below present ground level with a view to undertaking interventions that would be of immediate importance and interest for the creation of the Archaeological Park and for the site’s exploitation. The roads, lying just below the _humus_, were well-preserved and paved with limestone basoli of various forms and sizes. They were bordered by sidewalks paved either with small _basoli_ or large limestone slabs. Heavy subsidence indicated the presence of sewers below ground. The roads were delimited by polygonal terracing walls and the _opus incertum_ walls of the buildings facing onto them. The _domus_ had a double entrance on the street. In the interior it had an _atrium_, on the right side of which two doors led into a peristyle. The _cubila_ and _alae_ were arranged around the _atrium_ and peristyle, as was typical of the late Republican Roman _domus_. In the late Republican period the _domus_ was divided into two separate properties when the doors between the atrium and peristyle were blocked. The _domus_ which used the sector originally organised around the atrium showed signs of having a productive function. The structures of the _domus_, as far as preserved, were in limestone _opus incertum_, faced with white plaster. The floors were beaten limestone, _opus signinum_ or tile chips. All thresholds were single limestone blocks. The pools in the _atrium_ and peristyle were made from large slabs of moulded limestone, on which rested a border cornice of broken tiles. The pottery (very little apart from fragments of large containers, mostly dolia) and the construction techniques suggest that the occupation of the complex came to an end with the town’s dramatic destruction in 81 B.C.

In 2011, excavations continued in the urban area; in particular on the road running south-south west/north-north east, and the houses that were part of an interesting residential sector facing on to it on the east side. In previous years, excavations in the same sector had uncovered part of two domus with adjacent entrances on the road. Given that the houses communicated via two large doors, which linked the atrium of the second building to rooms of the first, they must originally have been a single property. Continuing on the north side of the road, the excavation uncovered another entrance to a third domus, adjacent to the others and linked to the central one by a staircase. This third house was also accessed directly from the street. The entrance led to an atrium with impluvium, which, off-centre with respect to the entrance, had a pool faced with large moulded tufa slabs. The rooms and the alae were arranged around the central area; the reception rooms and the kitchen were situated to the rear. The floors were either simple cement or with geometric decorations in the reception rooms and the cubicula, and of beaten earth in the service rooms. The plaster was mainly white and only very slight traces survived on the walls of the eastern sector. The walls were built in opus incertum with limestone chippings, in earth or with a socle of limestone blocks and standing structure in clay. The materials recovered during the excavation (study ongoing) mainly appeared to be part of large containers, amphora and coarse ware pottery. On the terrace uphill from the residential zone, the extension of the excavation area led to the discovery of a road on a north-south alignment, which starting from the entry plateau, met the decumanus at the height of the previously excavated domus situated below the small acropolis. The road, paved with limestone basoli, had a narrow sidewalk abutting a polygonal containing wall on the southwest side. The opposite side, which sloped slightly towards the road, was completely paved with limestone basoli. The excavation of the main road continued which from the Porta Serrone di Bove, runs in a straight line across the town as far as the staircase leading up to the small acropolis. In particular, the area in front of the baths characterised by a monumental crossroads was examined. The two roads at right angles, orientated north-south were of great visual impact. The road descending towards the south sector of the town, paved with limestone basoli, had a well-preserved sidewalk on both sides and the road surface itself showed a deep hollow caused by the collapse of the sewer below. The road ascending towards the baths plateau only had a sidewalk on its west side, paved in opus signinum. It was bordered on both sides by containing walls built of small limestone blocks of which only a few courses remain. The basalt paving of the road was rather uneven and characterised by a hollow caused by the collapse of a sewer below.

The research looked at the urban layout and a residential building, giving priority to interventions of use for the creation of the archaeological park. Excavation was completed of three roads that branched from the main road crossing the town on the north side below the small acropolis. All were paved with limestone basoli and showed evidence of having been restored. The first two branches below the small acropolis must have been used by traffic entering from Porta Maggiore. The first had no sidewalk and widened at point where a side road branched off to the east leading up to the small acropolis. In the final stretch, as it drew closer to the main road, it had a sidewalk on the east side. The second branch had a sidewalk on each side and a paved side street, closed to traffic, branched off from it at a right angle. The third branch road, headed north from the main road at the point where the latter was joined by the road from Porta Ninfina, and must have served the central part of the town. It was wider than the others were. Followed for 20 m, the road was paved in limestone basoli and had basalt sidewalks. The basoli were of varying shapes and sizes and the gaps between them were filled with limestone wedges. There was clear evidence of subsidence at the centre of the road, probably caused by the collapse of the sewer system below. A gravel layer constituting the new surface obliterated the paved road and the road itself was narrowed: an intervention that followed the destruction of large sectors of the town in 81 B.C. The investigation of the residential buildings in the _insula_ between the second and third branch roads, in the southern zone, looked at a vast _domus_, with complex construction phases, whose entrance opened onto the third branch road. The _domus_ presented a plan typical of the late Republican period: entrance divided into _vestibulum_ and _fauces_, _cubicula_ and _alae_ on the long sides and service rooms and reception rooms on the short sides, arranged around an atrium with an _impluvium_ built in tufa. Two passageways had been created in the two back rooms, which lead to a second open-air atrium, paved in _opus signinum_ with limestone inserts, at the corners of which four limestone column drums were found. At the end of the excavation, work was undertaken on the organization of the area: the holes in the paving of the first branch road were filled with limestone gravel to make it usable for visitors. In the _domus_, the floors were covered in order to provide a key to each room’s use: pink Carrara marble grit for the interior rooms; lapilli in the atrium and rooms opening onto it; white limestone grit for the _impluvium_ pool. Two routes for wheelchair bound visitors were created, which lead up to two viewing points overlooking the excavations. Relief maps with texts in Braille have been put up so that the site topography and a description of the remains are available for blind/partially-sighted visitors.

The 2014 excavations took place on the central plateau of the ancient city, to the north-east of the previously investigated residential sector of the II _traversa_ (_domus_ IV, V and VI). Delimited to the east by the I _traversa _ of the main city road leading from the Acropolis Minor, the excavated sector faced onto the road entering the city from the Porta Maggiore. The decision to intervene in this part of the archaeological park was dictated by the need to safeguard the ancient remains exposed by heavy rainfall during the winter. At the same time, the topographical location offered the possibility of extending the visitors’ route at its starting point. Overall, the investigated area covered 16 x 12 m and sloped steeply to the east. The excavation partially uncovered a _domus_ with the standard plan: _vestibulum_, _fauces_, and _atrium_ with an _impluvium_ faced with tufa slabs, around which a series of rooms were arranged (identified but not excavated). The _domus_ was entered via a low step leading into the _vestibulum_ directly from the road that led from Porta Maggiore to the plateau. The _vestibulum_ (room A), 3.50 x 1.50 m, was delimited by walls built with a footing of rough-hewn irregular limestone blocks (45 cm thick), bonded with earth with a clay matrix and paved in a mortar with crushed tile. The _vestibulum_ led into the _fauces_ across a limestone threshold. The threshold block, damaged in several places, measured 1.83 x 0.38 m and was delimited by two quadrangular blocks. The _fauces_ (room B), rectangular in plan, was paved in _opus_ _caementicium_ that continued in the _atrium_. The _impluvium_, slightly off-centre with respect to the _vestibulum_, was quadrangular in plan and faced with six overlapping tufa slabs. It had what was probably a well in the north-western corner that did not have a facing slab (not excavated). It measured 2.80 x 3.60 m and was characterised by mouldings created in order to direct the water into the drainage hole (diam. 15 cm) situated on the edge of the north side. All sides were damaged, in particular the southern part and all surfaces showed modern plough damage and some traces of burning. This winter’s heavy rain also uncovered a number of probable burials on the summit of the Acropolis Minor where at the beginning of the 20th century excavations brought to light an early medieval tomb. Therefore, it was thought advisable to undertake a surface cleaning of the entire sector in order to gain a better picture of the situation. The probable burials were situated in the area west of the long west side of the small temple, dug between the _basoli_ paving the road leading to the Acropolis Minor from the north-west. At least three graves were identified, denominated from north to south, tomb 1, tomb 2, and tomb 3. The latter, on a higher level than the others, was excavated in order to avoid its exposure by the elements. The skeleton, about 1.55 m in length, lay in a supine position. The right arm was folded across the abdomen, while the left arm lay along the side of the body. An iron nail was placed beside it. The skeleton was almost complete, only the extremities of the upper limbs were missing. The cranium lay to the west, resting on the make up for the _basoli_ that formed the border of the grave cut, at about 29 cm below the road surface. The cranium was tilted slightly forward to rest on the sternum. At the east end, in correspondence with the piece of limestone used as a grave marker, the extremities of the lower limbs lay at a depth of 22 cm.