I see only capitals here and wonder - does it have to be a capital of some country?
Time seems to be of the essence, the faster the negotiations the fewer casualties the war will have. Why don’t they just take the closest big city, which is easiest to reach? Or not even a city, just a place in an open field - I believe this is how negotiations were done 10 centuries ago, why is it different now?
Another, even more modern and faster option (thanks to @Trilarion) would be a video call.