Well! The British Museum seems to have quite a few engravings by Giovanni Battista De’Cavalieri online. Browsing them here, I quickly see that some come from a 1569 book entitled, promisingly, Urbis Romae aedificiorum illustrium quae supersunt reliquiae, i.e. Remains of famous buildings of the city of Rome. It contains some fascinating images.
Here’s the one of the Septizonium:
As far as I can undertand reading Emil Schürer’s impressive study on the planetary week (German: Die siebentägige Woche im Gebrauche der christilichen Kirche der ersten Jahrhunderte), the roman astrologer Paulus Alexandrinus had given his explanation of the Septizonium, i.e. each zone of the building was in strict relation with the relevant planet. Emil Schürer writes: “Zonen und Planeten gehören also eng zusammen. Jeder Planet hat seine Zone, und die Zone ist nichts anderes als der Bereich, in welchem sich der Planet bewegt.” (p.65).
Interesting – do you have a proper bibliographic reference for the Schurer book? I had trouble locating it.
I’d be interested to hear more about the Paulus Alexandrinus reference. Where may it be found?
You can find Emil Schürer’s study in “Zeitschrift für die neutestamentliche Wissenschaft und die Kunde des Urchristentums” Gieszen, 1904. Easy download with Archive.org, here: https://archive.org/details/zeitschriftfrdi92unkngoog
Reference about Paulus Alexandrinus at page 65 of above article of Schürer.
Oops! page 64, not 65.
Many thanks!