Since few architectural drawings and no theoretical treatises on architecture remain from the pre-modern Islamic world, the Timurid pattern scroll in the collection of the Topkapi Palace Museum Library is a valuable source of information. This text provides an analysis of the scroll dating from the late 15th or early 16th century, and aims to throw light on the conceptualization, recording, and transmission of architectural design in the Islamic world between the 10th and 16th centuries. It compares the Islamic understanding of geometry with that found in medieval Western art. The scroll, with its 114 individual geometric pattens for wall surfaces and vaulting, is reproduced in this volume. A catalogue includes illustrations showing the underlying geometries, in the form of incised dead drawings, from which the individual patterns are generated. An essay by Mohammad al-Asad discusses the geometry of the muqarnas and demonstrates by means of CAD drawings how one of the scroll's patterns could be used to design a three-dimensional vault.