Vincenzo Fasolo, "The Campo Marzio of G. B. Piranesi".
Redrawing History - archeological accuracy
...the Via Flamina and its odd placement in the Campo Marzio. Fasolo refers to the placement of the Via Flaminia as arbitrary. This then also brings into question the positioning of the Equiria, (which Fasolo wrongly identified as a waterway) and how the Via Flaminia today is actually the route inscribed by the Equiria of the Campo Marzio, and how the present day Corso, whose name refers to the ancient race course (I still have to verify this) is not depicted within Piranesi's Campo Marzio but the "arbitrary" Via Flaminia seems to take its place as the "main street" of the redrawing.
...note the locations in the Campo Marzio where Piranesi actually did excavation--this information is available in Lanciani's Forma Urbis Romae.
There is also the connection between the big scoop on the bank of the Tiber (depicted on the Nolli plan) and the Natatio (beach) at the same location in the Campo Marzio.
...a comparison between the Minerva Medica and the Horti Luciliani. Piranesi may be, at times, loose with what he puts where and what the buildings look like, but he is consistent in terms of finding his inspiration in actual Roman buildings.