Interventions of excavation and cleaning carried out on the two terraces of the sanctuary of Fortuna Primigenia at Palestrina have brought to light and clarified the architechtonic articulation and the hydric organization of this part of the sanctuary. The result of the evidence shows a single arrangement intended to gather the waters originating from the sanctuary of Fortuna and to collect them in the fountains and in the canals of the terraces beneath. Upper Terrace. The upper terrace, substructured with a wall in "opera poligonale" and paved with sheets of tufo, shelters a long façade animated with four or five absidal niches with semicolumns, which form a rich nymphaeum in the complex. The absidal niches contained fountains connected with canals which collected the water in the principal fountain of the lower terrace. Lower Terrace. This terrace too is substructured with a wall in "opera poligonale" and paved with sheets of tufo. At the center there is a fountain, a false grotto consisting of an absidal basin paved with sheets of tufo and covered with a semi-dome. The dome contains holes for a collection of hanging elements, perhaps false stalactites and false incrustations which camouflaged the mouth for the outflowing of the water. A smaller basin outside collected the water that overflowed from the larger. A shelter jutting out from the wall completed the facade at this point. The excavation undertaken in front at the canalization restored several architectural terracottas. Beneath the pavement level a series of oval grave pits were brought to light, apparently ancient. It was proposed that these were pits for the planting of trees, relative probably to a grove. A series of canals cross the terrace for the collection of the waters coming from not only the fountains but also from the roof of the Aula Absidata, to be channelled toward the complex. At the end of the 2nd century BC therefore the double terracing was animated by play of water and by a grove (sacred?), with substructures in "opera poligonale," crowned by parapets, cornices, aligned drip-stones and perhaps with architectural terracottas.