In this screenshot there is a city annex to Nottingham taking up a whole tile. Some 10 buildings are grouped around two central axis with a round square in the middle. There is a church like building on the right side, and a monument of sorts at the top of the axis. It seems a bit like an observatory with the round roof and the opening for the telescope, but there's no real explanation why an observatory should have such a support structure. It does not look at all like the trading posts that we've seen all over the place. At least I couldn't find this on Arioch's site or anywhere else. I doubt a wonder would take up a whole tile, so ... what is it?