Hello - I just wanted to weigh in on the sea city issue. I think in the short term the best option (take into account my lack of any truly useful modding info...but that's getting better) would be a world wonder that is a city. Maybe only buildable by a seafaring civilization? The city wouldn't be underwater, it would be a floating city. Or perhaps be an aquatic settler that upon founding the city, produced something like the fruit of Ygdraggsail (butchered, I know). A special resource that made the city feasible. Having the actual city float around could be very difficult, I imagine, but that would be excellent as well. For the record I would like to see sky fortresses as well. Floating castles, not cities, that have a few magical properties, and can transport x amount of troops. Also, it would not be able to be attacked by any unit without the flight promotion. (There should be a flight promotion once such units are available outside, of course, the hawk.) The flying castles would also be a wonder, I would think.