The church of Santa Maria Maddalena d'Alga is located in the historic center of Palermo and belongs to the monumental complex of the military district of San Giacomo, in the ancient western fortified area of the city. Today the area hosts a vast military complex, seat of the Command of the Carabinieri Legion of Sicily. The church is elevated with respect to the current floor. During some maintenance works of the church, for the installation of air conditioners, some georadar surveys were carried out to verify the presence of crypts or tombs under the pavement. The investigations made it possible to reconstruct a 3D georadar model and to identify some anomalies under the pavement. Some of these correspond to rooms that have been opened during maintenance work.