Ahi Çelebi Mosque, Istanbul

'The ancient mosque of Ahi Çelebi stands on the Golden Horn shore some 300 metres upstream from the Galata Bridge. It was founded at an uncertain date by Ahi Çelebi ibni Kemal, chief physician of the hospital at Fatih Camii, who died in 1523 returning from pilgrimage to Mecca. Standing outside the Byzantine sea-walls, the building was badly damaged by seawater that flooded and undermined it; Sinan restored it at an undetermined date, and further restorations have followed.' ¹

'Consequently no part of the fabric can be securely dated, but the effects of subsidence are plain: the astonishingly low, cave-like son cemaat yeri whose floor was raised against infiltration, and the extreme twisting of iron tie-beams between the arches. That vestibule is unique: two enormous squat piers and ten respond piers carry six small domes in an effect like the multi-domed Zincirli Kuyu Camii, and Freely wonders whether the original mosque consisted of just this area, around 1500. The present prayer hall has a large central dome on high-pointed arches springing from the same squat piers — possibly in part by Sinan — flanked by narrow aisles under quadrant vaults leaning like continuous buttresses, the whole the result of successive restorations shoring up unsure foundations.' ²