The ancient port of Banbhore is an important site of the Indus delta, near Thatta, still visible by its fortifications. It is one of the rare sites from Indian coast to the Red Sea to be inhabited from Parthians to Muslims (until XIIIth century (because aban-don following the Mongol invasion and change of the course of the Indus). Fortification of Banbhore is an urban military enclosure, adapted to the geographical environment (the site was probably surrounded by water). Full and semi-circular bastions, probably Sassanids or Abbasids (during reconstruction at the end of IXth century) are built on the massive enclo-sure. Many marks in the masonry and stonework suggest a reuse of an oldest city wall, probably Hindu/Parthian with square towers (as Sirkap, Taxila or Hatra in Iraq, but also by the Kushans in Kochambi (Uttar Pradesh, India). The two monumental gateways of the site are surrounded by two towers in Sassanid style. Because this principle of fortification will go back over by the Muslims (after conquest in 712), we question about the importance of the reuse of existing fortifications by Muslims? As well as the function of the defensive network of fortifications in delta of Indus, as Ratto Kot, surely to protect Banbhore.