 The Fatimid Caliphs competed with the rulers of the Abbasid and Byzantine empires, and indulged in luxurious palace building. Their palaces, their greatest architectural achievements, are known only by written descriptions, however. Several surviving tombs, mosques, gates and walls, mainly in Cairo, retain original elements, although they have been extensively modified or rebuilt in later periods. Notable extant examples of Fatimid architecture include the Great Mosque of Mahdiya, and the Al-Azhar Mosque, Al-Hakim Mosque, Juyushi and Lulua of Cairo.
