During the late Antique and Medieval eras, rare Eastern Christian churches were built with the apse decorated by a string or strings of niches. The study reveals the centers of initial development and the most important modifications of this architectural motif associated with the ancient Classical heritage. For the first time, the path of changing the shape and its role in the composition of the apse is traced, from Egypt in the south to Georgia in the north. Two outstanding works are recorded and analyzed in detail, because the architects of these churches made significant changes in adapting the motif to the aesthetics of a certain era. These are the early Christian church of El ‘Adhra (Holy Virgin, Yoldat Aloho) in Hah in the Mesopotamian province of Tur ‘Abdin and the late-10th-century cathedral of Ani, the capital of Armenia, built by an architect Trdat. In both of them, this motif is organically combined with a blind arcade. In Ani this topic could been appearance after its realization into the main church of Sanahin Monastery, but just the masters of Ani school became the authors of four known churches with the niches in apse. In a few units, the motif is widespread in Georgia as well. The assumption is put forward about the orientation of the architects of the large Georgian cathedrals of the first half of the 11th century to the Ani Cathedral in the matter of creating the composition of the apse. The features of other original compositions of a string of niches in the apses, which have not received further development, as well as the decoration of niches with a relief shell, are analyzed.