From the World Heritage inscription:
Tucked away amid the modern urban area of Cairo lies one of the world’s oldest Islamic cities, with its famous mosques, madrasas, hammams and fountains. Founded in the 10th century, it became the new centre of the Islamic world, reaching its golden age in the 14th century.
The highlight of old Islamic Cairo for me was the Citadel and the Mohamed Ali Mosque, which is the most elegant and beautiful mosque I’ve seen on my trip. This photo is of the inside of the mosque which rivals any of the great cathedrals of Europe.