http://www.threes.com/index.php?option=com_content&view=article&id=2077:three-holy-sites-of-islam&catid=81:religion&Itemid=61
Read carefully and take good notes.
Then look up each one separately if you need more information.
What were the three major cities in the Islamic world?how did each develop and grow to become important?
2 answers
What were the three major cities in the Islamic World