King Karl the not-so-great was concerned. He saw the River Flug as an easy pathway for his enemies to reach his land. So he decided to build a river castle narrowing the river and making his enemy unable to go up the River Flug, so they used the River Toov instead. The castle also provides an easy place to catch Flug trout and there's a restaurant on the second floor which provides good food and ale for only 1 groat.
The river is narrow, Huzzah!
Birds eye veiw