The first mosques in Anatolia were not built until the mid-twelfth century1 and they were generally fairly austere unornamented stone structures. It was not until the last quarter of the twelfth century that a significant programme of construction got underway, once the Rum Seljuq Sultan Kiliç Arslan II (d. 1192) had consolidated control over most of Anatolia. That is the point at which the chronological scope of this book begins, and it ends with the death of his grandson, Sultan ʿIzz al-Din Kay Kawus I (d. 1219–20). It was not just that the Rum Seljuq dynasty was engaged in the construction of monumental structures, but it was increasingly dominant in terms of both political power and architectural patronage. Over the course of less than fifty years, a corpus of buildings was constructed which blended forms and decoration developed in the Islamic architecture of Iran and Central Asia with the indigenous lithic medium of Anatolia. In the course of this process of synthesis, adoption and absorption, a number of unique structures were built and a definable aesthetic emerged across the region. Some of the newly introduced methods and motifs were absorbed into the architectural canon, whilst others withered and died. The hospital that ʿIzz al-Din founded in Sivas in 1217–18 is the last structure covered in this book. It may be viewed as the building that marks the end of the beginning with regard to the development of an identifiably Rum Seljuq architectural aes¬thetic in Anatolia. In the following decades building work continued unabated; indeed, it effloresced in the second half of the thirteenth century, following the Mongol victory at Köse Da© in 1243. In the latter phase the process of development became a matter of incre¬mental refinement within an established framework, rather than the synthesis of a new style forged in a crucible of cultural interaction and architectural innovation.