The Sado river empties at the city of Setúbal. From the Fortress of São Filipe, on the top of a hill, there is a magnificent view of the river and the beautiful Tróia peninsula. Setúbal has been a fish salting centre since the 1st century. After the Moorish invasions in the 4th century, it declined and the sands moved in. When Palmela was conquered from the Moors and handed over to the Order of Santiago de Espada, Setúbal was repopulated. In the 14th century the first line of walls was constructed but only parts remain. The town really developed during the Age of Discoveries. King Afonso V sailed from the port of Setúbal in 1458 for Morocco where he conquered Alcácer Ceguer. In 1580 Setúbal sided with António, the Prior of Crato, to no avail. Two years later King Philip II of Spain visited Setúbal and built the fort.

Setúbal was the most important commercial and industrial centre in the 19th century and was elevated to a city in 1860. In 1920 it became the District Capital.