Arches and domes

This lesson asks you to classify structures as solid, frame or shell structures. The museum offers two arched and domed structures, the chahartaq and the keel-arched dome of al-Azhar. It does not classify them itself, so the classifying is yours, and your class must bring other structures. ¹

To classify a structure, find what is solid all through, what is a frame of parts joined together, and what is a thin outer skin. Decide which describes each example and give your reason.

The record on the keel arch reports that in the qibla-arcade dome of al-Azhar, from the reign of al-Hafiz, the dome rests on keel arches over antique columns braced by wooden tie-beams ². Yeomans sees these features as defining Fatimid structure, much lighter than the solid brick piers of Tulunid building ². The chahartaq is a square domed chamber rising on four crossing arches ³; Rezavi's earliest Mughal example is the Kabuli Bagh Mosque, built by Babur at Panipat (c. 1527), where the chahartaq covers the central nave ⁴. The records describe and do not classify; the classifying is yours.

Yeomans sees the keel arches, antique columns and wooden tie-beams of the al-Azhar dome as much lighter than solid brick piers ². If you classified that dome as a solid, frame or shell structure, which part of Yeomans's description would you rely on, and why?

• The chahartaq: a square domed chamber on four crossing arches, and how it spread under the Mughals.
• The keel arch: a pointed arch shaped like an upturned boat, from Fatimid Cairo onward.
• Al-Azhar Mosque: the mosque whose qibla-arcade dome the keel-arch record describes.
• The Kabuli Bagh Mosque: Babur's mosque at Panipat, where the record says the chahartaq covers the central nave.

Read about the chahartaq and the keel arch. Sketch each and shade the parts you think carry the weight.