One of the only towns of any significance in southern Catalonia, Tortosa boasts a 10th century castle, some ancient fortified walls and a long history of conflict. Standing on the banks of the River Ebro, which has many times been the boundary between warring factions, Tortosa was originally established by the ancient Iberians who called it Dertosa, further changes were made by the Romans and even later by the Moors who held control of the town between the eighth and thirteenth centuries. The 10th century mosque built by the Moors was flattened and replaced by a Gothic cathedral after the reconquest. Much damage was sustained by Tortosa during the Spanish Civil War, and little of the old town remains, casualties were high and are still remembered by the inhabitants. Today Tortosa is more peaceful and is a popular day trip location enjoying pleasant weather, near by is the River Ebro Natural Park a significant wetland area, amongst other things the River Ebro is famous for catfish fishing, with these tough fish reaching huge sizes in this area. Map of Tortosa.