itruvor said:
The word "Castle" is better than the sign - # ...
Then I have a different opinion. For example there's Dortmund. It doesn't look like castle on the map plus I think it was a quite large city back then, so you can assume it's a city not a castle and then you go there and see it is a castle, so it's without marketplace or tavern. And it would be slightly strange to call it "Castle Dortmund" because I think that it was more a city than a castle in the XVIIth century. With my proposal we would have only names with "#" prefix which would let us easily distinguish castles from towns. You just look at map and know that each city with a "#" sign is actually a castle, not a city with tavern and marketplaces.