The composition is based on plate 63, Veduta del Ponte Salario, of Nuova Raccolta di 100 vedutine antiche della città di Roma, engraved by Domenico Pronti and first published in Rome in 1795. The bridge, dating from the Roman era, crossed the river Aniene, a tributary of the Tiber to the north of the ancient walled city. The medieval tower seen on the far side was demolished in 1829 and the central arch was blown up by papal troops in 1867. The loose arrangement of the irregularshaped tesserae of the plaque is complemented by the speckled markings of the black porphyry, probably from the quarries on Mons Porphyrites.

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