Madaris were established throughout the Islamic world, examples being the 9th century University of al-Qarawiyyin, the 10th century al-Azhar University (the most famous), the 11th century Niẓāmīyah, as well as 75 madaris in Cairo, 51 in Damascus and up to 44 in Aleppo between 1155 and 1260.
What is the most widely known madrasah?
al-Azhar University