This structure is one of two commemorative sabils built for deceased sons of Muhammad 'Ali. Ahmad Tusun died in 1816/1231 AH after contracting the plague and is buried in the family tomb,
Hosh al-Basha. His brother Ismail's sabil is located on the Bayn al-Qasrayn.
The decoration of the sabil is lavish and rococco, with wood, metal, marble, and painted plaster, in what would become a characteristic style of the Muhammad Ali period. The bronze grilles, wooden projecting eaves, marble inscription plaques, and wooden dome over the sabil room are particularly noteworthy. A two-story kuttab flanks the sabil on either side.
The building was restored by the American Research Center in Egypt from 1998 to 2002. During that restoration, a vast cistern for the storage of water was discovered under the sabil.
Sources:
Warner, Nicholas. The monuments of historic Cairo: a map and descriptive catalogue, 151. Cairo: American University in Cairo Press, 2005.
Williams, Caroline. Islamic monuments in Cairo : the practical guide, 163-164. Cairo: American University in Cairo Press, 2008.