This paper discusses a specific masonry technique used in the late ninth and early tenth centuries for the construction of arches and vaults in several buildings in Constantinople and areas directly influenced by Constantinopolitan building practices. The technique, as identified, appears to be restricted to building construction during this period alone, and as such could be viewed as representing a specific workshop tradition practiced in Constantinople. Further, its identification in other buildings could be useful in their dating to this same period. When the technique is found in building outside Constantinople, it might provide evidence for a direct association with and reliance upon building practices in the Byzantine capital during this period.