The Hajj pilgrimage, also called the greater pilgrimage, attracts millions of Muslims from all over the world and almost triples Mecca's population for one week in the twelfth and final Islamic month of Dhu al-Hijjah. In 2019, the Hajj attracted 2,489,406 pilgrims to the holy city. The 'Umrah, or the lesser pilgrimage, can be done at anytime during the year. Every adult, healthy Muslim who has the financial and physical capacity to travel to Mecca must perform the Hajj at least once in a lifetime. Umrah, the lesser pilgrimage, is not obligatory, but is recommended in the Quran. In addition to the Masjid al-Haram, pilgrims also must visit the nearby towns of Mina/Muna, Muzdalifah and Mount Arafat for various rituals that are part of the Hajj.