The first of the three great shrines of Islam is the Ka"ba at Mecca (al-Haram al-Makki al-Sharif). For Muslims, this mosque is the holiest spot on Earth. The mihrabs of all mosques are aligned with the Ka"ba so that all Muslims pray in the direction of Mecca. The whole of Islam can be seen as the spokes on a wheel radiating from the Ka"ba. This picture shows the rite of circumambulation, one of the rites of the hajj or pilgrimage. The lines inscribed in the pavement are circular as well.
The dimensions of the present Ka"ba, writes Cyril Glasse" in his book "The Concise Encyclopedia of Islam," are: the northern wall 12.63 meters, the eastern wall 11.22 meters, the western wall 13.10 meters, and the northwest wall 11.03 meters (it is not completely regular.) The Ka"ba height is 13 meters. The door on the northern side is 2 meters from the ground and is 1.7 meters wide.