Hassan II Mosque, Casablanca
The mosque is the third largest in the world. It can accomodate 105,000 worshippers (25,000 people inside and 80,000 outside) when the massive doors are opened electronically. "Built on reclaimed land, almost half of the surface of the mosque lies above sea water of the Atlantic. This was inspired by the verse of the Qur'an that states 'the throne of Allah was built on water.'" (Wikipedia) It was constructed in 6 years by 2,500 workers employed round-the-clock. The king also commissioned Moroccan artisans to create the intricate mosaics.