On the occasion of the 10th S.I.A. Congress of Archaeoastronomy, held in Trinitapoli (Bari, Italy) on October 22nd-23rd, 2010, this booklet is presenting the first results of our study on Celestial Architecture in the Villa Adriana (near Tivoli, Rome, Italy), which will soon be published in a forthcoming book.
Sometimes discoveries are made because of a fortunate event, and so it happened in the Accademia, in the large circular hall of the Temple of Apollo.
During our survey I had to discard a series of pictures because the shades were creating dark spots on the walls, and it was difficult to see their texture.
On june 11th, 2006, I was preparing for another photo session, when I saw a spot of light in the last panel (figure 1). At first I was annoyed, thinking that I would have to wait for half an hour for the Sun to move... but then I realized that the Sun was entering from a window on the upper floor, and it was perfectly illuminating the center of the panel on the ground floor, on the opposite site.
This could not be accidental: it was clear that the windows of the Temple of Apollo had been designed in order to create a sort of luminous ‘dance of the hours’.
This lucky episode marked the start of a research which ended up with the discovery of the archaeo-astronomical meaning of two buildings at Villa Adriana: Accademia and Roccabruna.
My first hypothesis, quite a simplistic one, was that the Temple of Apollo was oriented in such a way that at dawn the Sun would enter through a window in a room east of it, overlooking the town of Tivoli. I did not know anything about archaeoastronomy and astronomical orientations, therefore I was reasoning on geographical orientations, on the compass cardinal points; and east was not placed in the desired position.
The second hypothesis was that the Sun illuminated one after the other the wall panels on the lower floor, thus marking the hours of the day. If these panels had been twelve or twenty-four, things would have been much easier, because they could represent the hours of the day, or the seasons, the months or the signs of the Zodiac. But the panels are twenty, a number that does not match with any of these options.
Fortunately I asked the advice of Pietro Planezio, former director of the Astronomical Observatory of Genova (Italy). I showed him the plan of the Temple of Apollo, asking him to solve the problem and to find out which was the logic of the sun illumination on the walls.
The unusual number twenty of the panels puzzled him too; then he asked me to measure the angle between north and the window of the room where I thought that the Sun would rise at dawn. When I reported that it was 27° - a measure that had no particular meaning to me - he told me: “The Sun will never shine through that window. But 27° it is not an accidental measure! It means that the building is oriented towards the dawn of Winter Solstice and the sunset of Summer Solstice!”.
Thanks to him I met the scholars of archaeoastronomy, Giuseppe Veneziano (of the Observatory of Genova, Italy) and Mario Codebò (of Archeoastronomia Ligustica); we worked together wonderfully and our cooperation led to the publication of this book. We deciphered and studied the archaeo-astronomical meaning of Accademia and Roccabruna, which are located on the highest artificial Esplanade of Villa Adriana. We discovered the light phenomena that are still occurring during the Solstices in the area that was the true Acropolis of the Villa.
At Roccabruna we saw and confirmed the discoveries of the american architects Robert Mangurian and Mary-Ann Ray, who already in 1988 saw the ‘special luminous effects’ that were occurring on Summer Solstice1.
Villa Adriana has never been studied from an archaeo-astronomical point of view; our research is opening a new path for research in a completely unexplored field of studies.