A serapeum is a temple

Temple

A temple is a structure reserved for religious or spiritual activities, such as prayer and sacrifice, or analogous rites. A templum constituted a sacred precinct as defined by a priest, or augur. It has the same root as the word "template," a plan in preparation of the building that was marked out...

 or other religious institution dedicated to the syncretic

Syncretism

Syncretism is the combining of different beliefs, often while melding practices of various schools of thought. The term means "combining", but see below for the origin of the word...

 Hellenistic

Hellenistic civilization

Hellenistic civilization represents the zenith of Greek influence in the ancient world from 323 BCE to about 146 BCE...

-Egyptian

Ancient Egypt

Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...

 god Serapis

Serapis

Serapis or Sarapis is a Graeco-Egyptian name of God. Serapis was devised during the 3rd century BC on the orders of Ptolemy I of Egypt as a means to unify the Greeks and Egyptians in his realm. The god was depicted as Greek in appearance, but with Egyptian trappings, and combined iconography...

, who combined aspects of Osiris

Osiris

Osiris is an Egyptian god, usually identified as the god of the afterlife, the underworld and the dead. He is classically depicted as a green-skinned man with a pharaoh's beard, partially mummy-wrapped at the legs, wearing a distinctive crown with two large ostrich feathers at either side, and...

 and Apis

Apis (Egyptian mythology)

In Egyptian mythology, Apis or Hapis , was a bull-deity worshipped in the Memphis region.According to Manetho, his worship was instituted by Kaiechos of the Second Dynasty. Hape is named on very early monuments, but little is known of the divine animal before the New Kingdom...

 in a humanized form that was accepted by the Ptolemaic Greeks

Ptolemaic dynasty

The Ptolemaic dynasty, was a Macedonian Greek royal family which ruled the Ptolemaic Empire in Egypt during the Hellenistic period. Their rule lasted for 275 years, from 305 BC to 30 BC...

 of Alexandria

Alexandria

Alexandria is the second-largest city of Egypt, with a population of 4.1 million, extending about along the coast of the Mediterranean Sea in the north central part of the country; it is also the largest city lying directly on the Mediterranean coast. It is Egypt's largest seaport, serving...

. There were several such religious centers, each of which was a serapeion or, in its Latinized form, a serapeum ("seh-rah-peh-um").
31°10′55"N 29°53′49"E
The Serapeum of Alexandria

Alexandria

Alexandria is the second-largest city of Egypt, with a population of 4.1 million, extending about along the coast of the Mediterranean Sea in the north central part of the country; it is also the largest city lying directly on the Mediterranean coast. It is Egypt's largest seaport, serving...

 in Ptolemaic Egypt

Ptolemaic Egypt

Ptolemaic Egypt began when Ptolemy I Soter invaded Egypt and declared himself Pharaoh of Egypt in 305 BC and ended with the death of queen Cleopatra VII of Egypt and the Roman conquest in 30 BC. The Ptolemaic Kingdom was a powerful Hellenistic state, extending from southern Syria in the east, to...

 was a temple built by Ptolemy III (reigned 246–222 BCE) and dedicated to Serapis, the syncretic Hellenistic-Egyptian god who was made the protector of Alexandria.