In 2003, the Soprintendenza per i Beni Archeologici of Lazio appointed S. Piro of ITABC-CNR to undertake a georadar survey on the terracing situated east of, and 30m lower than the terrace on which the well known sanctuary stands. The structures recorded by the survey were excavated in the same year. These comprise an imposing, semicircular nymphaeum, probably built in the early Imperial period, overlying an open-air cistern of late Republican date. In front of the nymphaeum, beyond an open space delimited by lateral terrace walls, were the remains of what was probably a blocked doorway and a small side room with an opus spicatum pavement. This area terminated with a longitudinal terrace wall in opus reticulatum behind which was a terrace wall from an earlier phase, in opus quasi reticulatum, and on a slightly different alignment to the other structures. The last phase of terracing formed the back wall to a series of small rooms. In 2004 a terrace came to light in the area immediately below on which stood four rooms belonging to various building phases. Of these, room 1 must have had a series of tile built columns, and its west wall contained at least two semicircular niches: room 2 produced numerous fragments of painted wall plaster and black and white mosaic tesserae. Excavations were then undertaken in the area immediately above the sanctuary’s vast middle terrace, which revealed what was probably a passageway, connecting this terrace to those above, the west side of which is faced with opus reticulatum. On the south side of the structure were several slabs of tufa with channels cut into them. (Giuseppina Ghini – Francesca Diosono)