Siwa (both: sē`wä), oasis, c.35 sq mi (90 sq km), NW Egypt, in the Libyan (Western) Desert. Dates and tea are grown in the oasis, parts of which are c.200 ft (60 m) below sea level. Embroidery is also economically important. Siwah was the seat of the temple and oracle of Zeus Amon (Zeus represented with the horns of Amon). Alexander the Great visited the oracle.