Quoted from R. Landau, Morocco, Elek Books Ltd, London 1967 p.92 and 97:
Almost entirely enclosed by narrow alleyways, the mosque of Qarawiyin, [in Fes] like many an ancient European cathedral hemmed in by barrack like houses, is well-nigh unnoticeable from the outside.
It was founded by Fatima, the daughter of Muhammad al-Fihri, one of the early immigrants from Kairaouan in Tunisia. Her money enabled the erection of the mosque to begin in 859....
This building was enlarged in 956 by Zanata, Berber chief.... Further works [were carried out] on the mosque in 1135 and 1289...
Even in its early days, the Qarawiyin was famous as a centre of learning. Here it is claimed Gerbert [of Aurillac; the future Pope Sylvester II] first encountered Arabic numerals and the use of the zero, that is the decimal system.... Ibn Maimoun (Maimonedes) is also supposed to have studied for a time at the Qarawiyin. The list of those who gave lectures there include Ibn Khaldun, Ibn Khatib, Al-Bitruji, [and] Ibn Harazam
by: Quoted from R. Landau, Sun 21 July, 2002