In 1923 a small cluster of tombs was found on the northern side of the Isola Sacra.
The tombs are close to Portus, approximately 150 metres to the south-west of the Basilica
of Saint Hippolytus. In antiquity the tombs formed a whole with the other graves of
the necropolis, the "100 tombs". They are at a distance of a few hundred metres from those tombs.