The Oratory of the Souls in Massama, ancient Marsima, is located in a strategic position, probably along the 'via maxima', an important Roman road that connected Tharros and Forum Traiani (today's Fordongianus). This church has early medieval origins, with subsequent Romanesque interventions dating back to the 13th century. The structure is characterised by a cruciform plan, an architectonic element of considerable interest. Particularly noteworthy is the apse, which takes on a peculiar 'horseshoe' shape, giving the building a unique appearance. The octagonal tiburium adds further complexity to the architectural composition. The façade has simple and essential lines, dominated by an entrance portal with a minimal structure. The bell tower, made of fired bricks, may be a later addition, testifying to the different construction phases that characterised the history of this sacred building.