An Iseum, also spelled Isaeum, is a sanctuary (or temple) for the worshippers of the Greco-Roman god Isis

Isis

Isis or in original more likely Aset is a goddess in Ancient Egyptian religious beliefs, whose worship spread throughout the Greco-Roman world. She was worshipped as the ideal mother and wife as well as the matron of nature and magic...

. Isis was originally an Egyptian goddess who became hellenised. Many Iseums still exist today. They include the temple of Isis at Pompeii

Pompeii

The city of Pompeii is a partially buried Roman town-city near modern Naples in the Italian region of Campania, in the territory of the comune of Pompei. Along with Herculaneum, Pompeii was destroyed and completely buried during a long catastrophic eruption of the volcano Mount Vesuvius spanning...

, a dedication at the Egyptian complex at Philae

Philae

Philae is an island in the Nile River and the previous site of an Ancient Egyptian temple complex in southern Egypt...

, and a scattering around modern-day Italy.