Ebro Delta

The Ebro's mouth was an exposed entrance to the river country of southern Catalonia. During the fifteenth and sixteenth centuries, coastal raiders threatened both landings on the shore and movement upstream. Towers along the lower river and coast watched for approaching enemies and warned communities inland. Their positions linked the Mediterranean shore with the defended approaches to Tortosa and Amposta.

On the delta's southern side, Philip II ordered the construction of the Tower of Sant Joan dels Alfacs, probably around 1576, to watch over and strengthen the defence of the port of Alfacs. Its location beside the shallow bay placed surveillance close to the anchorage itself. Farther inland, medieval towers such as La Carrova guarded the river corridor. Together, these fortifications show why the delta's sea approaches mattered to settlements beyond the river mouth: a hostile landing could threaten the route into the lower Ebro valley.