From 1909 to 1912, French archaeologists led by Pierre Roussel carried out the first systematic excavation of structures in the neighborhood of the Inopos valley on the island of Delos. This was an area in which inscriptions related to the cult of Egyptian gods had been discovered as early as the seventeenth century, but with the exception of some incomplete digs in the nineteenth century, the exploration of a possible sanctuary dedicated to Egyptian divinities had taken a back seat to scholarly interest in the cult of Apollo. By the end of his excavations, however, Roussel had unearthed the third of three sanctuaries (A, B, and C) devoted to the god Sarapis. Roussel designated the last one of these that he found not Sarapieion C (as one might suppose from the order of their discovery), but Sarapieion A. He found the reason for this sequence in a lengthy Greek inscription that he uncovered there in 1912.

In prose and hexameters, this text, dated roughly to the end of the third century bce, tells of the sanctuary's foundation: a tale of humble beginnings, a struggle for survival, and ultimate success through the intervention of Sarapis. The most prominent event in this brief history is the victory of the Egyptian priest Apollonios over certain men who brought a lawsuit against him and the newly built sanctuary.