Beach city?

You build a city near a beach, research up to harbour then build that on a beach square.

So this is a bug? The game forbids to build cities on forest squares, so this should work with beach squares, obviously.

You can't build on beaches (other than the harbor). I imagine the sand makes for a poor foundation.

I think you built it on a land tile not a beach tile. Use raise land to turn the beach into grassland then you can build along the coast (just keep one ttile as beach to build your harbor)

You built it too close to your other cities that they use up the 5 square proximity restriction on usable tiles for city building.  Once you have another city within 5 squares of another city you can't build in that direction anymore and if said city makes it so the other side of your city is still within those 5 tiles you can't build from that city period unless it's a resource tile.

The game FORBIDS to place cities too close. If it allowed then it's considered OK. And this is the only city on which I can't build stuff. The game should just forbid building on beach tiles by default.

EDIT: OK, I see your point. It appears to be that there's really not much free space around that city. It will be made clear when I'll build my next beach city.

Global warming raising the sea levels, beach cities beware! lol. The "Harbour" *has* to be made on the beach tile. The harbour can be made on the cliff portion next to the beach, and you can train a transport unit, but it wont come out into the water..