One aim of the Portus Project has been to use geophysical survey to gain a better understanding of the Isola Sacra – an artificial island lying between the Tiber, Portus, Ostia and the Tyrrhenian sea. It was traversed by a road running between Portus and Ostia, and hosted a small settlement in the north with adjacent cemetery to its south.
The geophysical survey has revealed important new details about a major new canal between Portus and Ostia, the subdivision of the landscape into large fields for presumably pastoral agriculture, some structures associated with the marble yards (statio marmorum) of Imperial Rome, and tombs overlooking the Tiber. Of particular importance, however, was the discovery of a new northern sector of Ostia on the northern side of the Tiber. This area was composed of a suite of very four large warehouses and another large building that were shut off from the rest of the Isola Sacra to the north by a defensive wall. This discovery transforms our understanding of the topography of Ostia, lying to the south, although there are still uncertainties about the chronology of both the warehouses and the defensive wall.
When these results are considered alongside those from the initial 1998-2004 geophysical survey around Portus on the north side of the Fossa Traiana (Keay et al. 2005), they encompass a total of c. 350 hectares, and amount to one of the largest coverages of a port and its hinterland in the Mediterranean. The final report is shortly to be published (Keay et al. 2020).