Hassan II Mosque, Casablanca

Third largest mosque in the world (after Medina and Mecca), built in 6 years and finished in 1993.  10,000 craftsmen and 3,000 laborers worked 24/7 (in shifts) to make this a showcase of Moroccan craft.
This immense prayer room allows for 20,000 men to pray, on the mezzanine 5,000 women can pray, and another 80,000 outside on the marble plaza. An incredible work of art.