The Kaba is an imposing structure in the center of the Holy Mosque. It stands 50ft. high and is covered in an ornamental cloth called the Kiswah. This building is said to have been built by Abraham and his son Ismail by the order of Allah as a place of worship.

It has been rebuilt many times since, but according to Islamic tradition, the Blackstone is the only remaining piece of Abraham's original Kaba. The Kaba is the center of the Muslim world, as all Muslims must pray facing the Kaba at five specific times each day, wherever they are. Because of this requirement, the Holy Mosque is the only mosque in the world where prayer is focused inward towards the Kaba. The Kaba is such a sacred place, it is only entered twice a year for ritual cleanings. However, the Kaba itself is not worshiped, but viewed instead as a means through which the worshipers can express their reverence for Allah.