Geophysical investigations for the location of the Heptastadium in Alexandria (Egypt)

As concerns the links between ancient Alexandria and its famous light house on the island of Pharos, Strabo describes the so-caIled Heptastadium as "an embankment (which) forms a bridge extending from the mainland to the western portion of the island and leaves open only two passages ... which are bridged over; ...this work formed ... also an acqueduct...". Alluvium deposits on which now lies a -large part of the present city of Alexandria, have completely masked the traces of the Heptastadium: its position in the large existing isthmus was, till now, entirely conjectural and, from the middle nineteenth century, its orientation was believed to be largely different from that one of the antique streets network.