Casablanca's major highlight is undoubtedly the massive Mosquee Hassan II, on a rocky promontory, a couple of kilometres from the centre of the city.

The Hassan II Mosque (Arabic: مسجد الحسن الثاني‎) is the largest mosque in the country and the 7th largest mosque in the world. Its minaret is the world's tallest at 210 m (689 ft).

It stands on a promontory looking out to the Atlantic. A total of 105,000 worshippers can gather for prayer at the mosque simultaneously, 25,000 inside the mosque and another 80,000 on the mosque's ground outside. The building was designed by the French architect Michel Pinseau and built by Bouygues.

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." Part of the floor is glass and offers a view down at the sea. This feature was a result of King Hassan II declaring: "I want to build this mosque on the water, because God's throne is on the water. Therefore, the faithful who go there to pray, to praise the Creator on firm soil, can contemplate God's sky and ocean."

A spotlight shines in the direction of Mecca at night from the top of the minaret. The building also includes a number of other modern touches. It was built to withstand earthquakes and has heated floors, electric doors, and a sliding roof. The mosque displays strong Moorish influence and the architecture of the building is similar to that of the Alhambra and the Great Mosque of Cordoba in Spain. This and the old Tin Mal Mosque are the only mosques in Morocco that are open to non-Muslim visitors. Anyone are welcome to buy a ticket to view the interior on hour-long guided tours departing several times daily.

Work on the mosque was commenced on 12 July 1986, and was intended to be completed for the 60th birthday of the former Moroccan king, Hassan II, in 1989. However, the building was not inaugurated until 30 August 1993. During the most intense period of construction, 1400 men worked during the day and another 1100 during the night. 10,000 artists and craftsmen participated in building the mosque.

All of the granite, plaster, marble, wood and other materials used in the construction, were taken from around Morocco, with the exception of some Italian white granite columns and glass chandeliers. Six thousand traditional Moroccan artisans worked for five years to create the abundant and beautiful mosaics, stone and marble floors and columns, sculpted plaster moldings, and carved and painted wood ceilings.