The Episcopal Basilica, located in the very heart of late antique Philippopolis, quickly became the main landmark of the city’s urban topography. This was due to its eminence as the largest basilica in the province of Thrace, and the diocese, but also due to the growing importance of the metropolitan in the religious and secular life of the metropolis Thraciae, and in the ecclesiastical life of this part of the empire as a whole. It is no coincidence that the main events of the mid-fourth century to the mid-sixth century found their firm expression in one form or another in the basilica, its architecture and interior decoration. These events may explain its distinct early architecture (which is more closely related to that found in Italy), the changes that took place in the church interior in the last quarter of the fourth to the beginning of the fifth century (expressed through the mosaic floors), and the close relationship between the liturgy, interior decoration, and the constituent parts of the basilica. The location of the basilica in the hinterland of Constantinople allowed events in the capital to find their direct expression in its form and decoration. It can also be assumed that the reverse took place and that to a certain extent Constantinople was influenced by the Thracian provinces, although this influence was often refracted through the prism of the metropolitan requirements and tastes. By studying Thrace and Philippopolis, the scholar is also studying Constantinople; the metropolitan basilica in Philippopolis can provide information about processes that took place in the imperial capital about which data is otherwise extremely scarce.