Call to Prayer
The muezzin, or professional prayer caller, at the Madrassa of Sultan Hassan did a little demonstration of the acoustics in the liwan for us. And if I hadn't heard him do the same thing last year, I'd have been impressed - the guy's got a set of chops on him. But when he does it for tour groups for money, it's a little less impressive...
Ray took a video clip of his call to prayer, which you can see here.
Historic Cairo is World Heritage Site 89.