In June 2004, during work to install a heating system in the cathedral, the existing paving was removed. Over an area of circa 700 m2 the remains of two domus were uncovered, separated by a road (3 m wide). Of the southern domus eleven rooms were brought to light, one of which had a mosaic of diagonally laid white tesserae (0.5 x 0.5 cm) with a double border in black tesserae (1st century A.D.). All that was conserved of the other pavements were some make ups of greyish mortar, but finds of numerous tesserae suggests the presence of similar mosaics to the one found. Of the northern domus three rooms were partially uncovered, one of which conserved part of a mosaic similar to the one above. The existence of several Roman phases, suggested by alterations to the structures’ layout, was checked by specifically placed trenches which revealed the presence of an earlier building with different spatial division. These domus, which stood in the area immediately east of the forum, although already belonging to one of the town’s quarters, must have been of some importance. This is suggested by the mosaics but also by finds of painted wall plaster and fragments of high quality pottery and glass. The study of the finds shows that the domus were occupied between the Republican and late antique periods. The walls of the last phase were almost completely razed to the ground in the 5th-6th century A.D. in order to make way for the cathedral’s construction. Evidence of this intervention was provided by the layer of rubble from the demolition of the Roman buildings which was used to level the terrain. The first religious building was majestic in dimension and its interior was very richly decorated. The rectangular plan (25 x 45 m) was on a west-east alignment and terminated to the east in a semicircular apse. The internal space was divided into three naves by two colonnades built on a continuous foundation. The columns were 3 m apart and had reused Roman bases. The pavement was polychrome and black and white mosaic with geometric and plait motifs. This building occupied the most important part of the urban centre and seems to have remained more or less unaltered for a long time until, between the end of the 11th and beginning of the 12th century, construction began of the new Episcopal complex which to the present day characterises Città Alta. The new cathedral differs from its predecessor in its vertical set up and for the alternation in the naves of columns and pilasters. Placed inside one of the sarcophaghi found up against one of the cruciform pilasters were two adults and a number of objects: shoes of silk fabric with cork soles (13th century), a painted wooden staff and two lead figurines identified as amulets. Other burials were situated in the proximity of the presbytery. The cycle of frescoes on the wall which divided the main part of the cathedral from the presbytery showed S. Anna Metterza, S. Giovanni Battista, S. Pietro, S. Bartolomeo and S. Caterina. Datable to the second half of the 13th century it can be attributed to the so-called Maestro di Angera. In the second half of the 15th century, as is widely documented in the written sources, the decision was made to rebuild the cathedral, which by that time was partially below ground level due to the rise in the height of the ground level in the piazza. Filarete was commissioned to carry out the project. In the second half of the 17th century new work was undertaken, and with a few alterations to the original plan, the construction of the present building was completed.