The building of Roccabruna is located in a secluded spot, isolated from the rest of Hadrian’s Villa; it is reached via a path that starts from the Antiquarium near the Canopus and crosses a vast olive grove.
Only the lower level remains – a massive, quadrangular masonry ‘cube’ containing a large circular hall covered by a dome.
The upper level originally featured a small Temple with sixteen Doric columns surrounding an octagonal chamber, which was itself covered by a second dome.
Roccabruna had opus sectile and mosaic pavements, which prove tha
t it belonged the Villa’s noble buildings, frequented by the Emperor and his court. Very little has survived, however; for centuries, the building was abandoned and
was used by shepherds and farmers who lit fires inside it to keep warm. The name "Rocca-bruna" (literally "Brown Rock") is supposed to come from the dark, brownish color of the soot that blackened the walls and the vault.The main entrance on the lower level leads into
a large circular hall – RB6 – which measures nine meters in diameter. The floor was originally opus sectile, made of precious colored marbles; today, only the impressions remain, showing a pattern of concentric rows of triangles that decrease in size.
We can reconstruct the design by comparing it to a similar floor preserved in the National Archaeological Museum of Naples.
Opposite the entrance is a large central niche, which once housed a statue. Additionally, there are four smaller, semicircular niches positioned along the diagonals, alternating with two large rectangular niches –each featuring a window – and the niche of the main entrance.
At Roccabruna, a base for a candelabrum was discovered bearing th symbols of Isis – including the sistrum – which suggests that the structure was probably dedicated to the Egyptian goddess. We have therefore proposed a hypothetical reconstruction of its decoration, with a statue of the goddess Isis in a central niche, flanked by two candelabra. The walls were clad in precious marbles, while the dome may have been painted blue or adorned with glass mosaic tiles (tesserae).
A ramp, supported by a series of arches, still leads up to the Accademia Esplanade (Spianata dell'Accademia) and provided access to the small Temple of the upper level. Today, in place of that Temple, there is
a beautiful panoramic terrace; on clear days, it is possible to see the dome of St. Peter’s Basilica, which means that,
in Roman times, the Mausoleum of Hadrian could be seen (known today as Castel Sant’Angelo). On the opposite side, the Sanctuary of Fortuna Primigenia in Palestrina is also visible – a sight that held
a specific symbolic meanng, linked to the Sibyls and oracular sanctuaries of the area.Near the ramp, part of a
mosaic featuring a pattern of black and yellow lozenges remains; it was restored for the Great Jubilee of year 2000, but today it is not visible.
The small Temple on the upper level was graphically reconstructed by Lugli in 1940, based on scattered fragments of columns, entablatures, and the dome itself, remains that can still be seen on the ground onsite. It was accessed by a wide staircase, which survives to this day. Near the staircase here is
a small set of rooms, including a cubiculum and a latrine, probably intended for the temple’s priest.A stair descends to
an access corridor, where a fine mosaic with a yellow background remains, decorated with squares and rectangles outlined in black tesserae. Other steps lead down into
the cubiculum (bedroom), which still has a part of its central mosaic, decorated with white squares alternating with yellow rectangles. On the sides, there were two alcoves with plain yellow mosaics, left
undecorated since they would have been concealed by the beds. Near this chamber are the remains of a
private latrine, which formed part of that small, private living quarters.
The columns of the small Temple rested upon the three-meter-thick perimeter walls of the lower level, ensuring that no weight was placed on the dome of the hall in the lower level; the building thus featured two superimposed domes—a true "acrobatic" architecture.
Which was the function of this building? As we explain in our book
, «Villa Adriana. Architettura Celeste. I segreti dei Solstizi» (Italian editon only) the buildings of
Roccabruna and Accademia were dedicated to the cults of Isis/Fors Fortuna and Osiris/Dionysus. And the
Accademia Esplanade, the highest of the Villa, was its veritable
Acropolis: the sacred area of Hadrian’s Villa, closest to the divinity.
The book also features
the colorful mosaics and opus sectile pavements described above, as well as a series of previously unpublished photographs.
This hypothesis is based on ou
r studies in archaeology and archaeoastronomy, which led us to discover of
extraordinary illuminations (hierophanies) that still occur today within both buildings, during the Summer and Winter solstices (June 21st and December 21st).
The Temple with its large staircase bears a striking resemblance to a Temple depicted in
a fresco from Herculaneum, which shows a priest at the top of a flight of stairs, performing a sacrifice in honor of the goddess Isis.