Mecca is now best known for being Islam's holiest city, revered as the birthplace of Muhammad and the site where Allah first revealed the Qu'ran to him. Within Mecca is the Ka'aba, a building housed within the Al-Masjid al-Haram (Great Mosque) that is considered the holiest site, and wherever they are in the world, Muslims face in the direction of the Ka'aba while praying. A pilgrimage to Mecca is considered a necessity for devout Muslims at some point in their lives, and the city itself is off limits to non-Muslims. Indeed, Mecca is so integral to Islam that the name of the city has entered the English lexicon and is a commonplace reference to any area closely associated with something (such as Paris often being called the mecca of fashion).

Even centuries before the birth of the Prophet Muhammad, Jews settled in the area that became Medina to escape persecution at the hands of the Babylonians and Romans, meaning the area and its arid environment brought inhabitants precisely because it wasn't an attractive or resource rich area. In fact, the city fated to become the second holiest city in Islam earned that spot simply by straddling trade routes to the religious city of Mecca, which brought traders and pilgrims in large enough numbers to make it a trade center.

Jerusalem's particular importance to the religion of Islam is without question one of the major sticking points in the Israeli-Palestinian conflict. Prior to Israeli control, Jerusalem had been predominantly controlled by Muslim rulers since the 7th century and had been used as a type of political currency, legitimizing the ruling dynasty's claim over the city. For the world's Muslim population, Jerusalem is a holy site because Muslims believe the Prophet Muhammad visited Jerusalem where he ascended to heaven during the famous "Night Journey." There was also a period of time during the Prophet's life when Muslims prayed in the direction of Jerusalem, as opposed to Mecca.