The Mosque-Madrassa of Sultan Hassan is a massive Mamluk era mosque and madrassa located near the CitadelCairo. Its construction began 757 AH/1356 CE with work ending three years later. At the time of construction the mosque was considered remarkable for its fantastic size and innovative architectural components.    Yesil Mosque                                                      Entrance with moc+írabe half-dome.
Sultan Hasan's low profile seems inconsistent with the massive undertaking that was his mosque, but the mosque's grandeur makes sense given Sultan Hasan's dramatic life. Sultan Hasan ascended the throne at the age of 13 in 748 AH/1347 CE. Upon taking over the reins, Sultan Hasan placed people of his own favor into positions of power. This happened at the expense of dignitaries currently in position; it upset many of them and caused a mutiny within the empire. Discontented Emirs arrested the Sultan in 1351, held him in jail for three years, and promoted his brother Salih to the throne.
He returned to power and again reshuffled the ruling establishment attempting to solidify power, but Sultan Hasan was assassinated by his commander in chief of the army, Yalbugha al-‘Umari, a Mamluk thought to be loyal.Because of the Sultan's extravagance in spending fortunes on women and other forms of favoritism, the commander rebelled against the Sultan.
Little information is available about the construction of the mosque of Sultan Hasan. The most substantial source available is al-Maqrizi writing six decades later. He had access to administrative documents that are unavailable to historians today.
The construction of the minarets is of particular interest. Plans called for four minarets, but only three were ever constructed. One of the minarets collapsed and three hundred people were killed. Al-Maqrizi noted that the minaret's fall ignited conversation across Cairo and Fustat about the impending downfall of the state.
The mosque was built close to the Citadel, on the site of the Palace of Yalbugha al Yahawws. This was meant as a pleasing site for the Sultan to look down on from his palace in the Citadel.
The sheer size of the mosque set it apart. Al-Maqrizi noted that the height of the large iwan was superlative. It measured 65 cubits, five higher than another notably large mosque, the Iwan of Kusraw at Al-Mada'in in Iraq. Several unique features about the mosque should also be noted. Al-Maqrizi noted that the great dome that was not equalled in Egypt, Syria, the Maghreb, or Yemen. Despite the thickness of the mausoleum walls, the dome was made of wood. The mosque's dome was of an uncommon shape, that of an egg. The positioning of the mausoleum between two minarets was quite novel.
The extravagant interior and the impressive facade of the mosque did little to hide the fact that it was built during a particularly hard time for the Sultan. Having undergone and experienced a particularly tough time the mosque is one of the few good reminders of Sultan Hassan’s reign.