Saudi Arabia
Saudi Arabia has cities that are important to the Muslim religion.  Many Muslims from around the world visit Mecca in Saudi Arabia to make a pilgrimage.  The pilgrimage is one of the "pillars of Islam".  Other big cities are Riyadh, Jeddah and Dammam.  The pilgrimage is called hajj in the Arabic language. Somebody who makes a pilgrimage to Mecca is called a hajj in the Arabic language. People who are not Muslim are not allowed to enter Mecca.