The Canopus is one of the most famous and unique buildings of Hadrian's Villa. It was preceded by a long water basin called Euripus, where the statues of Caryatids and Silens were found along one of its sides, during the excavations of the 1950s; today the statues are replaced by copies, the originals are in the nearby Antiquarium.
At the end of the Euripus canal stands the so-called Serapeum, whose main hall – visible from afar – was a sort of artificial grotto in the shape of a semicircle, covered by an umbrella semi-dome, typical of Hadrian's architecture, and in particular of Hadrian's Villa.
In the center there is a crescent-shaped brick podium, called stibadium, which served as a triclinium bed on which the guests lay down. This hall, in fact, was a monumental triclinium where the emperor Hadrian received important guests by offering spectacular banquets, enlivened by music and dance.
At the center of the triclinium opens the so-called Antrum a sort of grotto, which goes into the hill and is partly covered by a barrel vault. There, in a dominant position, the emperor Hadrian took his place with his most important guests. The position was the same of a royal box in terms of acoustics and sight.
At the end of the Antrum there is a niche still covered with fake stalactites (tartari) from which water flowed and filled a rectangular basin located behind the stibadium. The water cascaded from that basin and was collected in a semicircular canal that surrounds the stibadium.
In that same canal other water flowed from two niches with stair-fountains that can be seen in the walls, alternating with other semicircular niches for statues. All the water of the fountains at the end flowed into the long canal of the Euripus.
The large triclinium was completely covered in precious marbles that have disappeared along with the statues and many columns; the dome and the barrel vault of the cave seem to have been covered in colored mosaic.
In the Serapeum of the Canopus, Egyptian sculptures depicting the goddess Isis and her priests were found, which are now in the Vatican Museums.
The space in front of the Triclinium had a small stage where actors, dancers and musicians entertained guests with shows and concerts, songs, dances and music. The large dome worked as a sounding board, the acoustics were perfect.
In this grandiose Triclinium, summer banquets were held in the evening, in the cool, with the magic flames of the torches that were reflected in the basin of water in front.
The semi-dome was an artificial cave, a ‘virtual’ reproduction of real and spectacular triclinium caves such as that of Tiberius in Sperlonga, which was imitated by many emperors.