The Masjid al-Haram — the Grand Mosque or Sacred Mosque — is the largest mosque in the world and the centre of Islam's holiest site. It surrounds the Kaaba, the cube-shaped structure towards which Muslims pray worldwide. The mosque has been expanded repeatedly by Saudi authorities to accommodate the growing number of pilgrims; current capacity for simultaneous worshippers runs into the hundreds of thousands, with millions circling the mosque precincts during peak Hajj.
At the heart of the mosque stands the Kaaba itself — draped in black silk embroidered with gold Quranic calligraphy. Pilgrims perform tawaf by circling the Kaaba seven times counterclockwise. Adjacent to the Kaaba is the Maqam Ibrahim (Station of Abraham) — a glass-encased stone believed to bear the footprint of the prophet Ibrahim — and the well of Zamzam, from which pilgrims drink. The mosque is open continuously; during Hajj the crowd density can be dangerous, and the authorities manage flows with barriers and police.
The enormous expansion projects, particularly the Clock Tower complex built in the 2000s and 2010s, demolished significant historic Ottoman and early Islamic structures around the mosque. Historians and conservationists have criticised the loss of heritage in the name of pilgrim capacity.