Muslim pilgrims perform circular movement around the Kaaba as a part of the Tawaf ritual during the Hajj. Many try to reach the Kaaba to touch the Black Stone, and then return to continue their Tawaf. (a) The pilgrim indicated by the circle is trying to return to continue his Tawaf. (b) This pilgrim is continuing penetrating the opposing pilgrims. (c) The pilgrims are about to join the others performing the circular movement. (d) The pilgrim’s trajectory is illustrated.