3rd-century BC architecture

thumb|Remains of the Serapeum of Alexandria thumb|Marble bust of Serapis, Roman copy after a Greek original from the 4th century BC A serapeum is a temple or other religious institution dedicated to the syncretic Greco-Egyptian deity Serapis, who combined aspects of Osiris and Apis in a humanized form that was accepted by the Ptolemaic Greeks of Alexandria. There were several such religious centers, each of which was called a serapeion/serapeum () or poserapi (), coming from an Egyptian name for the temple of Osiris-Apis ().