Situated between the Port to the north and the Ostia Antica excavation site to the south, Isola Sacra is the land that Trajan transformed into an artificial island through the creation of a canal, called Fossa Traiana or Trajan's Ditch, linking the Tiber to the sea. In the first century A.D. a road linked the centers of Ostia and of Porto, by crossing the island which constituted the intersection of these main roads. 

Along the road a necropolis developed, the Porto necropolis, that was never reported in the old documents and was discovered between the 1920s and 1940s when the territory was reclaimed. Another interesting site to visit on the Holy Isle is the Basilica of Saint Hippolytus and the Antiquarium dedicated to the Porto martyr Hyppolytus, between the end of the IV and the beginning of the V centuries.