Immediately after the Scenographia, it is two plates of maps serially depicting the historical build-up of the Campus Martius that Piranesi presents in the Il Campo Marzio publication. This series of historical maps is then followed by the Ichnographia Campus Martius.
The earliest map of the Campo Marzio, representing the era from 750BC to 500BC, features the Equiria, the Palus Caprae, the Ara Martius and the Terentus among a few other structures.
The Palus Caprae (or Capreae) was a site within the Campus Martius in ancient Rome. The name means "Goat Marsh" or "the Goat's pool." In myth, the Palus Caprae was the place where Romulus underwent ascension into godhood. The marsh was fed by a stream called Petronia, but by the Augustan period it had disappeared or been drained. The Palus Caprae was in the small basin where the Pantheon was later built...
The second map, representing the Campus Martius from 500BC to 225BC, features:
8. Carcer Cl. X. Vir. ,
8. Basilica Caij et Lucij,
9. Villa Publica,
10. Aedes Apollin.,
11. Templum Bellonae,
13. Aedes Herculis Musarum,
15. Septa Trigaria.
The third map, representing the Campus Martius from 225BC to 44BC, features 14 temples along with:
17. Circus Flaminius,
22. Porticus Corinthia cn. Octavij,
23. Porticus Metelli,
31. Porticus Minucia,
32. Domus Pompejana,
34. Horti prius Pompejani deim Marci Antonii,
and various sepulchers.
The fourth map, representing the Campus Martius from 44BC to 14AD, the era of Augustus.
For the most part, these maps coincide with the textual content of the Il Campo Marzio publications, which is Piranesi's (architectural) history of the Campo Marzio, evidenced almost entirely with references to ancient texts. Only occasionally does Piranesi delineate the plan of a building within these maps which otherwise has no historical backing.