Technically Abyssal Ruins was a castle too. You also have Relic Castle in the desert, and N's castle. So B/W had castles covered XD
I dunno. They don't exactly have to base it off france, not that we even have confirmation that it is france. The "tower" in the back grounds reminds me of Radio Tower. Since its in a large city it can be a radio station. A tower like that can be in any large city in any country.