This building, now inaccessible, was a sabil – a charity distributing free drinking water from an underground cistern. There were hundreds of such charities in mediaeval Cairo, usually combined with an elementary school placed above. The very ornate one attached to the mosque/madrasa in the centre of Qaitbey’s complex is a typical example. This building, however, is very unusual in being covered with a stone sail dome. In one wall is niche that once contained a salsabil: a carved marble slab over which water would cascade so as to cool and aerate it. The niche is crowned with a fine hood of five tiers of muqarnas niches carved in stone, but the marble salsabil is gone. The sabil’s huge window opened onto a street that passed through the gateway at the northern end of the rab‘ of Qaitbey. This lane has now disappeared. A similar building stands at the other end of Sultan Qaitbey’s complex, but it appears that that structure was not a sabil.