Piuss description of the cathedral is one of several accounts he gives of buildings constructed at his request as a Pope. He describes the difficulties encountered by the builders, provides a brief description of the churchs external and internal layout, and also makes several aesthetic observations concerning proportions, illumination, and decorations.
We can read in the document a series of references to the canons of Italian Renaissance architecture, with an emphasis on the classical model of ancient temples, which is explicitly embraced. In order to be able to trace outside architectural influences, we must first note that Italian Renaissance did not produce a unique, monolithic style, but rather, it consisted of a variety of local aesthetic and architectural styles, which frequently juxtaposed and influenced each other, as they did with other, non-Italian styles…(short extract)