Al-Masjid al-Nabawī, "Mosque of the Prophet"), often called the Prophet's Mosque, is a mosque built by the Islamic Prophet Muhammad(pbuh) situated in the city of Medina. It was the second mosque built in history and one of the largest mosques in the world. Architecture and Special Structures: As it stands today, the mosque has a rectangular plan on two floors with the Ottoman prayer hall projecting to the south. The main prayer hall occupies the entire first floor. The mosque enclosure is 100 times bigger than the first mosque built by Muhammad(pbuh) and can accommodate more than half a million worshippers. The mosque has a flat paved roof topped with 27 domes on square bases. Holes pierced into the base of each dome illuminate the interior. The roof is also used for prayer during peak times, when the domes slide out on metal tracks to shade areas of the roof, creating light wells for the prayer hall. At these times, the courtyard of the Ottoman mosque is also shaded with umbrellas affixed to freestanding columns. The roof is accessed by stairs and escalators. The paved area around the mosque is also used for prayer, equipped with umbrella tents. The north facade has three evenly spaced porticos, while the east, west and south facades have two. The walls are composed of a series of windows topped by pointed arches with black and white voussoirs. There are six peripheral minarets attached to the new extension, and four others frame the Ottoman structure. The mosque is lavishly decorated with polychrome marble and stones. The columns are of white marble with brass capitals supporting slightly pointed arches, built of black and white stones. The column pedestals have ventilation grills that regulate the temperature inside the prayer hall. This new mosque contains the older mosque within it. The open courtyard of the mosque can be shaded by folded, umbrella-like canopies, designed by Bodo Rasch and Buro Happold.