Islam is the second largest religion in the world in terms of number of followers. It is the last religion to come out of the Middle East Abrahamic tradition. Islam has spread mostly in the Middle East, Asia, Africa and Europe while the other continents also contain Muslim populations. Islam has given the world great architectural and artistic contributions. Most of the Muslim holy sites are very popular for pilgrims and other tourists alike. Here are the top 10 Muslim holy sites in the world.