the hall with daytime sunlight and allowing worshippers to pray under the stars on clear nights. It weighs 1100 tons and can be opened in five minutes; it measures high, with an area of . The roof is covered with cast-aluminium tiles, (similar to the Fez tiles), stronger and more reliable than traditional ceramic tiles, and about 35 percent lighter. The prayer hall is also illuminated by light from the glass gates on the northern wall. Minaret At in height the minaret is the second tallest minaret in the world. It has a laser beam fitted at the top, which is electronically operated in the evening. It is oriented towards Mecca, across the sea and has a range of . The minaret is said to enhance the visual alignment of the boulevard. It is square in shape thrusting skyward. The base to the top width ratio of 1 to 8 (between basement and the summit) has a marble covering on the exterior with austere decoration. The faces of the facade have carved ornamentation with different materials. There are stitches of roudani tracetine on a 100,000 MP surface. This decorative material (with chrome and green as dominant colours), is a substitute for the use of bricks, the material used in many other notable minarets, and has given the mosque an extraordinary elegance. Green tiles decorate the minaret for one third of the height from the top, and then changes colour to deep green or turquoise blue; it is said that in the Hassan II minaret, the designer had used his sea-foam green and God's blue to celebrate the life of a king. The concrete used for the minaret was a special high-grade type, which could perform well under severe conditions of a combined action of strong wind and seismicity. This was achieved by the Science Department of the Bouygues Group, the contractors for the project, who developed an extra-strength concrete four times stronger than ordinary concrete. Called B.H.P (highly resistant concrete), it offers a resistance to compression value of 1200 bars per sqcm (claimed to be a world record) and has a very quick setting time. This enabled the building of a taller structure with due underpinning of the foundation, while adhering to the construction schedule. Cranes were also designed to suit the height of the minaret for concreting. Hassan II Mosque Museum The museum opened its doors to the public