South of the baths there is a valley with a long pond surrounded by a splendid colonnade. At the bottom end stands a nymphaeum that is recognizably a temple of Serapis (Serapeum).
It consists of a semicircular exedra with a ribbed cupola, extended by a long vaulted corridor. This ensemble, which is decorated with fountains and statues, was for a long time believed to be an evocation of the Egyptian town of Canopus, linked to Alexandria by a canal from the Nile and famous for its Temple of Serapis.
A more recent interpretation gives it another meaning: the pond is not the canal but the Mediterranean, which explains the presence of Greece (symbolized by copies of the caryatids from the Erechtheion in Athens) and of Asia (represented by copies of two Amazons by Phidias that adorned the Temple of Artemis in Ephesus and a copy of Praxiteles' renowned Venus of Cnidus).
The architectural complex at the bottom of the lake is seen as symbolizing Egypt; at least that is what one may deduce from the three sculptured groups that decorated it, the layout of which is reconstructed in the Vatican's Egyptian Museum.
Its composition consisted of Osiris-Apis in the center, Isis-Demeter at the back and, on the walls, several repetitions of Antinoüs, Hadrian's young favorite who, after his premature death in Egypt in 130 AD, was deified by the Emperor.
Allow time to visit the small museum beside Canopus to see the items discovered during the excavations of the 1950's.