The Zisa is a castle in the western part of Palermo in Sicily, southern Italy. It is included in the UNESCO Arab-Norman Palermo and the Cathedral Churches of Cefalù and Monreale World Heritage Site.
The construction was begun in the 12th century by Arabian craftsmen for king William I of Sicily, and completed by his son William II. The edifice had been conceived as summer residence for the Norman kings, as a part of the large hunting resort known as Genoardo that included also the Cuba Sottana, the Cuba Soprana and the Uscibene palace. Joan of England, Queen of Sicily, widow of William II, was confined to the palace by the new king Tancred of Sicily due to her backing Princess Constance aunt of William II to ascend the throne.
The Zisa is clearly inspired by Moorish architecture. The name Zisa itself derives from the Arab term al-Azīz, meaning "dear" or "splendid". The same word, in Naskh script, is impressed in the entrance, according to the usual habit for the main Islamic edifices of the time.
In the 14th century merlons were added, by partly destroying the Arab inscription which embellished the upper part of the edifice.