Castelo de Castro Marim is located in the village and parish and municipality of the same name, in the District of Faro, in Portugal.
Raiana fortification, in a dominant position on the so-called Monte do Castelo, defended that crossing point on the right bank of the mouth of the Guadiana river, opposite the Castle of Ayamonte on the opposite bank, today in Spain. Ex-libris of the village, it is considered by scholars as one of the most significant monuments of the Portuguese Middle Ages in the landscape of the region. It is integrated in the Sapal de Castro Marim and Vila Real de Santo António Nature Reserve, and the panoramic view over the river, the Sapal area, the Algarve mountains, Spain, the salt flats and the beaches of that coast is very much appreciated.