The Mysterious Case of the Portum Traiani Sestertius (15 min)

Presenters

Rabun Taylor, University of Texas at Austin

Abstract

Recent work on the well-known sestertius of Trajan representing the inner harbor of Portus, one of the emperor’s most famous construction projects, has improved understanding of both the coin’s dating and its historical context. But one feature of the coin, which dates to 112–114 C.E., remains mysterious: the appearance of the port’s name, PORTVM TRAIANI, in the accusative case. It is argued that the choice of this unique legend was quite deliberate and that it probably referenced a public display map in Rome. Either an update of Agrippa’s famous map of the known world, or more likely an entirely new creation celebrating Trajan’s projects of infrastructure and imperial expansion, this map, like others of its time, borrowed many of its urban place names from itineraries, which tended to represent cities and other features along roads and sea routes in two of the three locative cases: ablative for point of departure and accusative for destination. The famous set of four silver cups from Vicarello are inscribed with slightly varying itineraries of this kind, each extending from Gades (Cádiz) to Rome. Maps such as the Peutinger Table adopt a similar itinerary style, representing most place names in oblique cases. Portus may have been shown on this map as on the coin, highlighting Trajan’s new hexagonal inner harbor as seen from above. To make the reference more memorable the coin would thus have replicated the legend on the map, which represented Portus as the celebrated terminus of converging maritime itineraries.

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