The Mosque of Ibn Tulun

Ibn Tulun sits in the Sayyida Zeinab district, south-west of the Citadel. From the street it is a blank fortified wall; you go in through a gate, cross an outer enclosure, and then the space opens.

The courtyard is enormous — the mosque covers more ground than any other in Cairo — and on most days there will be a handful of people in it.

The scale and the silence. There is nothing in the courtyard except the domed ablution fountain in the middle and the arcades around the edge. No later infill, no clutter, no crowd. Of all the great buildings in Cairo this is the one that gives you room, and the effect of walking into it is why people who live in the city keep going back.

Then the minaret. It has an external staircase spiralling around the outside, which exists nowhere else in Egypt and is generally understood as a memory of the great minaret at Samarra in Iraq, where Ibn Tulun grew up. You can climb it, and the view takes in the Citadel, the Mosque of Muhammad Ali on its ridge, and the roofs of the old city.

The detail is worth slowing down for too: the crenellations along the parapet, cut so they read like rows of small standing figures, and the carved stucco on the arch soffits, which is Abbasid rather than Egyptian and unlike anything later in Cairo.

Ahmad ibn Tulun was sent from Samarra as governor of Egypt for the Abbasid caliphate and made the province effectively independent. He built a new administrative city, al-Qata'i, and this was its congregational mosque, completed between 876 and 879.

Almost all of al-Qata'i was destroyed afterwards. The mosque is essentially the only thing left of it, which makes it the oldest mosque in Cairo still standing substantially as it was built. Older structures survive in the city — the Nilometer on Rawda Island, the Roman walls of the Fortress of Babylon — but no other mosque of this age has come down so nearly intact.

It is built of fired brick covered in carved stucco, not the cut stone that later Cairo used, and it is fronted on three sides by an outer enclosure — the ziyada — that holds the streets back from the mosque walls. There is no ziyada behind the qibla wall, which originally abutted Ibn Tulun's own palace, the Dar al-Imara. The domed fountain in the centre of the courtyard is a Mamluk replacement, added when Sultan Lajin restored the whole building at the end of the thirteenth century.

The arcades are carried on brick piers rather than on columns salvaged from older buildings, and the arches they support are pointed — more than two centuries before the pointed arch became standard in Gothic Europe. A carved wooden frieze of Qur'anic text ran below the arcade ceilings.

By the late thirteenth century the mosque had fallen out of regular use. Sultan Lajin, who the chroniclers say hid in the derelict building while a fugitive, restored it in 1296, and the minaret now standing is usually assigned to that campaign rather than to Ibn Tulun's own builders. Systematic repair came only with the Comité de Conservation des Monuments de l'Art Arabe, set up in 1881.

• The spiral minaret with its external staircase, and the view from the top
• The open courtyard, roughly 92 metres square — Ibn Tulun covers more ground than any other mosque in Cairo
• Abbasid carved stucco on the arcade arches
• The crenellations along the parapet, cut like rows of figures
• The Gayer-Anderson Museum, built into two houses against the outer wall
• Arcade windows filled with pierced stucco grilles, few patterns repeating
• Pointed arches on brick piers, not columns taken from older buildings