This paper records new observations concerning the meaning or ‘ideological message’ of two, at the visual surface, completely different types of monuments in Constantinople. The great imperial columns of Late Antiquity are discussed in relation to two Mid-Byzantine square floor mosaics based on the geometric theme of circle-in-square, one in the imperial cathedral in Istanbul and one close to the imperial summer palace at Hebdomon outside the city walls. The transition from monumental corporeal three-dimensional objects to two-dimensional diagrammatic patterns, is discussed in relation to the broader question of Iconoclasm and Islamic influence on the development of Byzantine symbolism and pictorial representation of ideas. The possible incorporation of an Eastern abstract way of representing ideas of cosmology and royal power, into Byzantine architectural symbolism in Constantinople, will tentatively be demonstrated by changes in the formal language and appearance of these monuments, however in a Western Christian context. The basic Roman imperial message seems present but increasingly disguised.