Topographic survey at Portus

This survey records the shape of the ground surface, and creates a context for the geophysical survey results, enabling us to relate geophysical anomalies with the lie of the land and the many standing structures. Much of the site had already been surveyed by the Soprintendenza Archeologica di Ostia, who produced a digitized 1: 2000 map that was used as a base map. Further topographic survey was necessary in areas that fell outside of the area of the Soprintendenza survey, where greater precision was needed, or where a comprehensive micro-topographic survey was required to record changes in ground height caused by buried archaeology.