Being facetious on the internet is hard.

Without even looking at your post beyond the slight skim I will say yes, I know the ottoman conquest in 1453 is why Hagia Sophia is a mosque/museum today.  Many ottoman mosque were pretty much are copies of the Hagia Sophia, something I keep finding amusing.

Speaking of the Hagia Sophia, the Hagia Sophia likely exists as it was made in the 500's.

Not sure about San Vitale.  Maybe under a different context?

Anyhow, as a fun little thing to know the Romans had hot wax tablets they wrote in.  The name stylus is derived from the tool Romans used to etch Latin in the hot wax.  Not sure why I wanted to say that, but in this TL I wonder if hot wax based writings/manuscripts are still around as opposed to the parchment used in the Middle Ages.  I am not sure if hot wax was also used in the Middle Ages, I suspect in some areas but I am oblivious of it.