The Hassan II Mosque is located in Casablanca . It is the largest mosque in Morocco and the third largest mosque in the world after ( i ) the Masjid al-Haram ( Grand Mosque ) of Mecca and ( ii ) the Al-Masjid al-Nabawi ( Prophet 's Mosque ) in Medina . The Hassan II Mosque is a religious buildings in Casablanca , Morocco , the largest mosque in the country and the fifth largest mosque in the world after the Masjid al-Haram ( Grand Mosque ) of Mecca and the Al-Masjid al-Nabawi ( Prophet 's Mosque ) in Medina .