I now have several Skylanders (thanks to my son's PS3 game) and all but one island unlocked, and I've built several community buildings, but when I visit other people, they have a different look to some of them, like the Great Hall. Is it possible to upgrade buildings? My current level is 25.
Not really, Orville's summoning building can be upgraded plus a new one only just being released if you complete a challenge.
Sorry I don't know why the buildings look different.