Mértola (altitude:85m/280ft) is picturesquely set on the slopes above the left bank of the Guadana, joined here by its tributary the Oreias, about 70km/43mi northwest of the coastal border town of Vila Real de Santo António. In Roman times the site was occupied by the town of Mirtilis, mentioned by the Alexandrian geographer Ptolemy (second C. A
.D.), which later had to give way to a Moorish stronghold.
Townscape
With its narrow and twisting alleys Mértola is still rather Moorish in appearance. From the main square its narrow streets, lined with little white houses, lead uphill to the parish church and then on up to the castle.