The Kaaba, [b] sometimes referred to as al-Ka'ba al-Musharrafa, [d] is a stone building at the center of Islam's most important mosque and holiest site, the Masjid al-Haram in Mecca, Saudi Arabia. [2] [3] [4] It is considered by Muslims to be the Baytullah (Arabic: بَيْت ٱللَّٰه, lit.