Umayyad conquest of Hispania
The seat of the municipality is the town of Mértola, which has around 2800 inhabitants (2011), located on a hill over the Guadiana River. Its strategic location made it an important fluvial commercial port in Classical Antiquity, through the period of Umayyad conquest of Hispania: Mértola's main church (the Church of Nossa Senhora da Anunciação) was the only medieval mosque to have survived the period in Portugal.