Though Cairo has many modern and nondescript suburbs, the oldest districts of Al-Qahira are well-preserved and exhibit some of the finest period architecture in the Islamic world.
The Islamic world does not have any fine examples of architecture.  
mnli hypothesis: The Islamic world does not have any fine examples of architecture.   premise: Though Cairo has many modern and nondescript suburbs, the oldest districts of Al-Qahira are well-preserved and exhibit some of the finest period architecture in the Islamic world.