...researched Gaius Flaminius because Piranesi's inversion of the Circus Flaminius within the Ichnographia. It turns out that Flaminius did go against the grain of the Senate and was of plebeian background. Sue Dixon also mentioned that Piranesi uses Flaminius as a point of subdivision in his Il Campo Marzio text of the districts history, (Piranesi actually thinks highly of Flaminius and his circus), and she (Sue) noted how the via Flaminia is not correctly delineated within the Ichnographia--the circus and the road were built by the same man. Perhaps Piranesi chose to delineate both these entities incorrectly to accentuate that Flaminius, in going against the grain, began a new effect on the land use of the Campo Marzio--thus showing the circus rotated 90 degrees in order to make it stand out. As for the Via Flaminia, there is no immediate explanation as to why it meanders off into a totally wrong direction, but it is worth noting the many plebeian homes that Piranesi situates along the street; this may be a reference to Flaminius' own plebeian background.
There is also the area called Prata Flaminia (within which the Porticus Philippi is situated) and I'm not sure if Flaminius also donated this land to the city/citizens.