Mecca is where Abraham built the Ka'aba, and some believe he did so in order to rebuild the Bait-ul-Allah that had originally been built by Adam. This is the building that every Muslim around the world faces in prayer up to five times per day. The prophet Muhammad was born in Mecca in 570 A.D., linking the city to Islam forever.
According to Islamic tradition, Muhammad started to receive divine messages in 610 AD and started to preach monotheism to believers of animism. In 630 A.D., Muhammad conquered Mecca and destroyed all 360 idols at the Ka'aba and rededicated the building to Allah.
Millions of people make a pilgrimage to Mecca every year. There are two major pilgrimages that Muslims make every year, including the Hajj and the Umrah. The Hajj is a pilgrimage that all Muslims should make once in their lives as long as they are of sound health and financially able to make the trip. It attracts about 3 million believers every year, of which 11,000 are American. Umrah can be made at any time of the year; however, it is more common around Ramadan. The Umrah is not obligatory to Muslims, but is recommended by the Qur'an.