It is interesting how imagination works differently for different people, and for the same person at different times or stages in their life.
I am thinking of what comes to mind when one thinks of a place, person, book, event, or even an historical situation - the last one is the most fascinating, since it is such a large and complex things to 'imagine' (say) the life of a Roman on Hadrian's Wall, or the University of Paris at the time of Thomas Aquinas, or Concord Massachusetts when Emerson and Thoreau were neighbours.
I personally find that for some things the memory is usually based on a static image, like a photograph; or perhaps more exactly, something rather more like a short segment of video, lasting a few seconds.
So, for the last example of Concord, I have a picture of Emerson's study with its Aeolian Harp; a picture of sitting in the doorway of Thoreau's hut looking out at gentle rain; and a scene of lounging beside a very slow flowing river, in a meadow, on a summer afternoon.
But for Constantinople at the height of the Eastern Roman Empire I have something more like a feeling, an emotion experienced here-and-now induced by the imagination of being there.
The actual imagined place is neither a picture, nor a video, but includes a vista of the city in its setting, the impression of light reflected from sea, marble, through windows and from rich colours and gold - set below a solidly blue sky; choral singing and processions with crosses and icons aloft - all bound-up in that kind of entranced yearning which C.S Lewis called joy and the German Romantic called Sehnsucht - but knowingly directed at Heaven.
The specific details of what is imagined are vague, perhaps because they seem more like an inferred explanation of what might serve to induce the emotion, rather than being a causal stimulus of the emotion.
It seems, therefore, that the reason that I have such an affinity for Byzantium is precisely due to the strength and quality of this imagination of the time and place.
What I get from it is a sense of what it would, could or might be like to live in a place which I and those around me considered to be a representation of Heaven-on-Earth - yet which always pointed above and beyond itself to the eternal reality of Heaven itself.
To be able to imagine this has (it seems to me) done more to sustain and direct my Christian faith than has a great deal of cold reason.
This is, for me, the reality of Byzantium and a pinnacle of earthly Christian life - and the facts concerning abstractions such as political and religious structures, publications and biographies... these seem arbitrary, uncertain and irrelevant by comparison.