was added in the central courtyard at the end of the thirteenth century by Mamluk Sultan Lajin instead of the "fauwara". (see also Chahartaq (architecture)) Interior The interior arched windows provides natural light against the hollow dome. Each pointed arch has a window and is designed with plain geometric design. Minaret There is significant controversy over the date of construction of the minaret, which features a helical outer staircase. It is also told that using these stairs one can climb up on a horse. Legend has it that Ibn Tulun himself was accidentally responsible for the design of the structure: supposedly while sitting with his officials, he absentmindedly wound a piece of parchment around his finger. When someone asked him what he was doing, he responded, embarrassed, that he was designing his minaret. Many of the architectural features, however, point to a later construction, in particular the way in which the minaret does not connect well with the main mosque structure, something that would have been averted had the minaret and mosque been built at the same time. Architectural historian Doris Behrens-Abouseif asserts that Sultan Lajin, who restored the mosque in 1296, was responsible for the construction of the current minaret. The minaret shows influences from both the Lighthouse of Alexandria and the famous minaret in Samarra. It is built entirely of well-fired red brick, plaster, and carved stucco. Stucco is cement-based plaster that is mixed on-site and applied wet which hardens to a very dense solid. The mosque is also built from this material. The staircase extends up to the tower 170 feet in height. Prayer niches There are six prayer niches (mihrab) at the mosque, five of which are flat as opposed to the main concave niche. It indicates the qibla which the profession of faith inscripted in Kufic calligraphy. The main niche is situated in the centre of the qibla wall and is the tallest of the six. It was redecorated under Sultan Lajin and contains a top of painted wood, the shahada in a band of glass mosaics and a bottom of marble panels. The same qibla wall features a smaller niche to the left of the main niche. Its stalactite work and naskhi calligraphy indicate an early Mamluk origin. The two prayer niches on the piers flanking the dikka are decorated in the Samrarran style, with one niche containing a unique medallion with a star