From casablanca : 

Casablanca, Morocco‘s commercial centre. Tends to come lower down on the tourism list, behind the likes of Marrakech and Rabat. However the city’s French colonial legacy, entwined with the traditional Arab culture. Ensures there’s lots of diverse things to do and see. Alongside the art deco buildings, and old stone medina alleys, visitors can find museums, palaces, and the second largest mosque in the world.
Hassan II Mosque
Completed in 1993 and located on a platform overlooking the Atlantic Ocean. The iconic Hassan II Mosque is the second-largest mosque in the world, and one of few open to non-Muslims. (through selected guided tour opportunities lasting around an hour each).

Furthermore, This building can accommodate up to 25,000 worshipers, offers Muslims the chance to pray on a glass floor. Also,  giving the unique feeling of praying directly over the sea. Everyone is welcome to admire the beautiful piece of architecture at any time from the spacious courtyard, which alone can accommodate a further 80,000 people.