Qal’at al-Marqab is among the most imposing and most important crusader castles in the levant and possesses one of the largest medieval chapels built on a military site in the Latin East. Despite its widely acknowledged significance, it has been the subject of only a few, mostly historical studies with, until now, no archaeological work having taken place there. The Syro-Hungarian Archaeological Mission (SHAM) began a full-scale research project on the site in October 2007 with a multi-disciplinary team made up of historians, archaeologists and archaeozoologists, art historians, experts in geology and geophysics, architects and conservators of objects and frescos, together with laboratory experts, with the aim of getting a better understanding of the site and its evolution through almost a millennium. ¹ Among the dozens of research zones inside the castle and its suburb, special attention has been devoted to the castle chapel that proved to contain far more scientific data and artistic treasures than anticipated (Fig. 2.1).