Around 1165 the king Guglielmo I financed the construction of the summer residence of his court: the castle of the Zisa (from the arabic term “al-aziza,”roughly translated as “the gorgeous”). The palace is designed entirely in Islamic-style architecture, featuring ogival archways, muqarnas, vaulted niches, and even a perfectly functional air conditioning system. The architect who designed the building used many devices to create a comfortable place to relax during the scorching heat of Sicily’s summer. The castle faces north-east, so that the ample fornices in the first level could capture the temperate winds coming from the sea, and a large pool in front of the building, connected directly to the main hall’s interior via a further decorated pool with flowing water, provides the necessary humidity to keep the air fresh. The remaining upper levels also feature a system of vent ducts connected with the lower vestibule, in order to create a constant air flow through the entire building. Finally, thick walls and small windows help keep a stable internal temperature.