Rione IV Campo Marzio on Tavola 4, spreading from Piazza del Popolo and the Pincio gardens down the Tiber bank towards Parliament.
Source: Old map, public domain
The oval of Piazza del Popolo sits at the northern tip, with the Pincio terraces and Porta Pinciana along the hillside edge. A circular enclosure numbered 44 stands where the Mausoleum of Augustus lies, and Ponte Cavour crosses the curve of the river on the left.