This temple was built in the Hellenistic period. The stonework of the altar and the writing technique of epigraphs in the area also prove that the building was constructed in the 3rd century B.C. It is located on the terrace south of the theatre, on the south Athena Street. The building was supported by a 5 meter high terrace wall which displayed an excellent stone workmanship. It is 14.60 meter long, 7.31 meter wide and the altar is 1.73 meter high.
The sanctuary was dedicated to Egyptian gods which is understood from the epigraphs found there. In the epigraphs Egyptian god names included such as Isis, Serapis, Osiris, Anubis and Harpocrates. According to the inscriptions on the wall of the propylaeum and the detailed information on the cult, the rites should have been conducted by an Egyptian priest or by Isis. If these rules were not violated, the punishment was defined as 100 drachmae. But the Prienean people were not familiar with this tradition.
Coming of the Egyptian priests to Priene can be explained in two ways. Either during the Laodicean War (246 – 241 B.C.) King Potelemy III of Egypt tried to bring the Aegean region under Egyptian rule, or when Priene had commercial relations with Egypt wanted the Egyptian businessmen to dedicate this sanctuary to Egyptian gods.