Take away Sultanahmet. Get rid of the delicious food and colorful markets. You can even have the City Walls, if you’d be so cruel. Even without most of the major tourist sites in town, Istanbul would still be one of the prettiest cities in my world.
Truly, the crumbling Ottoman churches and mosques are beautiful. The waterways, center of the city for centuries, add so much. But even the newest parts of the city still seem to be dotted with minarets and mosques and beautiful colors and appealing textures.
To be honest, the look and feel of the city actually comes close to rivaling Hong Kong for me. Thats about as high a compliment as I know to pay.