Mértola

Mértola stands above the Guadiana at the river's farthest inland port, linking the Alentejo to maritime routes. Its walls, castle and old riverfront bear witness to a settlement shaped by Roman, Christian and Islamic rule. The remains of a late antique religious complex include a basilica and baptisteries; the Islamic town left a mosque and a quarter within the citadel. After the Christian conquest, the mosque was adapted as a church. Its horseshoe arches and other features of the earlier building survived the change of worship, while later alterations gave the interior a Manueline character. The river continued to define Mértola's position between the southern plains and the sea.