The building is an original construction, the result of a fusion of different cultures: Roman-Hellenistic, Byzantine, Lombard and local. For this reason, it embodies the pluralism that was typical of the early Middle Ages - in all its expressions - and that would be the foundation of medieval Europe.
It is structured in three naves, with a tripartite presbytery, which in the central area is covered by a vaulted structure on an octagonal base. The two apsidal ambulatories on either side of the main apse surpass it in length and create a façade effect on the back.
With respect to the interior decoration, there are still traces of the stuccoes on the counter façade and some elements of the pictorial apparatus. A gem-covered cross, from whose arms are hanging chains with A and Ω, is depicted in the back of the central niche.
On the façade, the three central windows are outlined by fluted pilasters with capitals decorated with phytomorphic motifs and surmounted by small pediments.
The three portals are delineated by frames with classical motifs and surmounted by a richly worked entablature flanked by large volutes.
A peculiar feature of San Salvatore is the very strong presence of spolia, the use of which has a dual connotation due to the fact that some parts were reused as such (columns, bases, capitals, internal architrave), while others underwent a radical reworking (decorative elements of the façade, the frame in the presbytery and nuts at the basis of the cupola).
