Wondrous Sound

I generally post a photo here but a while back I was visiting the mosque and madrasa of Sultan Hassan in Cairo with a friend when one of the men offered to show us how the construction of the mosque facilitated the transmission of sound from the area where the sheikh would be preaching to the people sitting in the large courtyard. This mosque was built in the 1100's long before anyone could dream of microphones, but the effects are extraordinary.