Work on the expansion of the Prophet's Mosque in Madinah was launched by King Fahd in 1985 (1405/06 AH) and the Mosque can now accommodate in excess of one million worshippers at the busiest times. A unique feature of the expansion project was the development of the 27 main plazas. Each plaza is now capped by a state-of-the-art sliding dome, which can be rapidly opened or closed according to the weather and can be used in unison or separately as required. Elaborately carved stone friezes decorate the domes, and the plazas have been paved in decorative geometrically patterned marble tiles. The project also necessitated the building of six additional minarets, each 105-meter construction crowned with a 4 ton gold-plated crescent.