In terms of typography the book of Onofrio Panvinio is structured mostly as full pages of text spread. The font of the body stays the same throughout the whole writing. I would classify the chosen font as classical and rather small. It is noticeable that the overall layout of the pages is really compact, as we can see from the moderate to small margins chosen and the little spacing within the text. Some headings and subheadings are to be seen, which are printed with the same font as the body while simply varying size, depending on the value of the part it is indicating. It is important to note that the author rarely starts a new chapter with a new page, but carries on directly after the end of the previous chapter.
Regarding illustrations, the only two present are portraits of two different figures, who appear to be popes. Those illustrations are both centred on one full page, one above the other, and are framed in an oval shape. A legend of a few lines accompany each of them which allows the reader to understand who are the person represented. Except those two, illustrations are absent throughout the whole book, Onofrio Panvinio does not represent buildings or any architectural details in his work.
From the reduce number of illustrations, we can infer that images are almost insignificant compared to the text in Onofio Panvinio’s book. Considering his choice of typography and compact format, Le Sette Chiese Principali di Roma is a work to be read rather as a hand book.