The Castle Marvão is found at an altitude of 843 meters previously mentioned sea level in one of the best peaks with the Serra de San Mamedi, which is called Serra di Sapoyu, Alentejo, Portugal, whose slopes are steep and inaccessible. You can reach the Castle within the east only. https://www.tripspoiler.com/2020/12/castle-marvao-alentejo-portugal.html