Portugalete is near the mouth of the River Nervion and, before the river was channeled to make it navigable to Bilbao, it was an important port. There is an attractive waterfront, and in the old town stands the Gothic Church of Santa Maria which dates from the 16th Century and has a museum. Nearby is the Torre de Salazar, a tower which was built in the 14th Century and housed a prison on one of its floors.