The Great Mosque of Mecca (Masjid al-Haram Expansion Project)

Located in Mecca, Saudi Arabia, the Great Mosque of Mecca, known as Masjid al-Haram, surrounds the sacred Kaaba and serves as the holiest site in Islam. To accommodate millions of annual pilgrims during the Hajj and Umrah pilgrimages, the Saudi government initiated the King Abdullah Expansion Project. Costing an estimated 26.60 billion dollars, the monumental expansion encompasses extensive multi-level prayer halls, massive pedestrian piazzas, automated ventilation tunnels, high-capacity escalators, and sound amplification networks. Engineered by the Saudi Binladin Group alongside international architectural consultants, the complex features advanced civil infrastructure, including automated sunshades and specialized central cooling plants. The expansion adds over 400,000 square meters of interior floor space, dramatically increasing total mosque capacity to more than 2.5 million worshippers. The development required unprecedented urban site clearing, extensive subterranean tunneling into adjacent granitic hills, and marble craftsmanship sourced from quarries in Italy and Greece. Ranks first globally as the most expensive architectural development on Earth with an estimated expansion project cost of $26.60 billion. Key benchmarks: Nominal Construction Cost: $26.60 billion; Inflation-Adjusted Cost: $30.00+ billion; Location: Mecca, Saudi Arabia; Pilgrim Capacity: 2.5+ million worshippers.