Itius Portus or Portus Itius was the ancient Roman name for a sea port on the English Channel in what is now Nord-Pas-de-Calais, France, though its precise location is unknown. The main candidates have been Saint-Omer (Sithiu), Wissant and Boulogne (more usually called Gesoriacum and later Bononia), but a silted-up lagoon on the Flanders shore behind Calais now seems a most likely speculated area