SOLVED. Adult Sci-Fi. A future where Constantinople is the center of the world. [s]

[BD]

Hi everyone,

I have seen this book maybe 14 years ago in Paris (2007), in a small bookshop selling English books.

I don't remember the author, the title, the cover image (not hardcover). The author's name was definitely British/American.

The only detail that I remember is that "Istanbul/ Constantinople* (I guess it was mentioned like this*) was the capital of the world and there was an International Federation (?)... It was in Sci Fi section, but as you know they are always mixed with Fantasy books (a world which I do not know well)-

I was so sure to be able to remember it, I haven't taken any note. Apparently I've forgotten it and can't remember since years-

Any suggestion would help- I am so curious (probably because I still can't find it!!)

Thank you in advance!

Stay safe-

[Joseph]

Well, let's start.
There’s Agent of Byzantium, by Harry Turtledove.

And The Gate of Worlds, by Robert Silverberg.

[BD]

Wow!

That was definitely "The Gate of Worlds" by Robert Silverberg-

(I can't believe I couldn't find it among Silverberg's books!)

Thank you so much- 👍🏻