The Eşrefoğlu Mosque in Iznik was destroyed during the Turkish War of Independence, not long after Cornelius Gurlitt published a black and white photograph of its facade taken by G. Berggren. The photograph constitutes the only remaining visual evidence of a building whose initial construction likely dates to the lifetime of the shaykh whose memory it preserved. The flamboyant facade shown in the photograph reveals a unique mass of calligraphy, including inscriptions, published many years ago but revisited here. These inscriptions add to our understanding of the mosque’s history. My own telling of the phases of the building’s construction involves a reexamination of the identity of the mosque’s Ottoman dynastic patrons, principally Gülbahar Hatun, mother of Sultan Bayezid II. The inscriptions also raise questions about the shaykh’s spiritual legacy. Finally, the mosque’s spatial relationship to a nearby dervish lodge and to türbes associated with the shaykh and his family, buildings that also no longer survive, can be newly addressed.