A large round tower might also be nice for a medieval castle.. or just as a single tower.
The size could be 2x2 like a steckhouse, but round and three floors high with rounded battlements and the possibility to put a ballista on top of the tower, or another siege machine.
I like this idea and would really like to see a large medieval tower, either like a Norman keep with four small towers at the corners of a single large tower or a later round design. Castles always sell well and Playmobil hasn't really done Norman knights, so this would be a good opportunity to do so.
A 50s theme would be fun but I don't know how well it would sell.
I mentioned the Greek theme at the beginning of this thread and still would love to see it. I see the large set being a Greek temple, the medium sets being a Greek ship and a Trojan horse, and the smaller sets being a two-person two-horse Greek chariot, a group of Athenian warriors, and a group of Spartan warriors. If not, I'd settle for a single Hoplite Special.
