Hundreds of thousands of Muslims are flocking to the holy city of Mecca in Saudi Arabia to perform the Hajj pilgrimage, which takes place this year from October 13th to 18th.
Dressed in white clothing and in a state of ritual purity, they have come from all over the world to participate in one of Islam's five pillars, an obligation for every Muslim who is physically and financially able to do so.
The faithful begin by circling the Kaaba seven times in a ritual called tawaf. Muslims believe that the Kaaba was built by Abraham and his son Ishmael.
They walk between the hills of Safa and Marwa seven times, to commemorate the struggles of Abraham's second wife, Hagar, who frantically ran from one to the other searching for food and water for her child. Her prayers were answered when baby Ishmael's heel hit the ground and a spring, Zam Zam, miraculously sprang from the desert.