the portrait of Piranesi
There is a portrait of Piranesi engraved by his son Francesco. The portrait is a profile set in a medalion, and the overall composition of the plate is in the Piranesi style. In the lower left corner, there is a stone fragment carved with plans, and it is indeed a fragment of the Ichnographia, specifically the Theater of Marcellus, the Minutia Vetus, and the Porticus Octavae. ...wonder if Francesco, or even Piranesi himself, saw the Ichnographia as Piranesi's greatest achievement. The four-sided Temple of Janus is also clearly delineated on the fragment.
...a case for the father-son theme that begins with Mars and Romulus (inversely God, the Father and His Son Jesus), and could include Augustus and Agrippa, and Trajan and Hadrian, and even Theodosius and Honorius.
Pagan - Christian - Triumphal Way