Muqarnas 42 begins with a remembrance by Professor Gülru Necipoğlu of András Riedlmayer (1947–2026), who, starting in 1985, served for thirty-five years as the Bibliographer and Director at the Documentation Center of the Aga Khan Program for Islamic Architecture in Harvard’s Fine Arts Library. Over the years countless Muqarnas articles benefitted from his expertise and learned suggestions. The articles in Muqarnas 42 span more than ten centuries, covering topics such as lusterware in ninth- and tenth-century southern Mesopotamia, the Genoardo of Palermo, Mamluk helmets, and inscribed tomb covers of nineteenth-century Morocco. This volume also features recently discovered evidence concerning the provenance of the so-called Piyale Pasha Iznik-tiled lunettes. Authors include Lina Bellanca, Umberto Bongianino, Peter Christensen, Shireen Ellinger, Deniz Erduman, Nazan Ilgaz, Pedro Jiménez, Julio Navarro, Melis Taner, Alison Terndrup, and Rebecca Wrightson.