I'm so excited. I think I've just found something from my childhood that I've been seeking for years. When I was in my early teens (maybe 13), I went to a Polish festival and picked up a book filled with the folk tales of Poland. I remembered they were a little gruesome, but fascinating. I have no idea what happened to the book over the years.
In one of my Google searches for this book, I finally think I've stumbled on one of the tales from it. In fact, I may have found the book. It's called "Legends of Poland: The Legend of Popiel and the Mice." The book is part of a series of "Legends of Poland." The art looks somewhat similar to my memories and the tale was definitely one I read. I remember the book being a collection of stories, but it's quite possible my memories are faulty and it was a series of books instead.
The story is about King Popiel, a Polish king who is incompetent. His own family tries to have him killed. Afterward, Popiel is convinced by his German wife to kill his uncles and dump their bodies in a lake. It was done, but the people revolted and Popiel and his wife escaped to their tower on a lake. But Popiel couldn't escape. Rats and mice rose up from the lake and ate through the tower to devour the royal couple.
You can find out about the legend at the Wikipedia entry. Here's a Czeslaw Milosz poem called "King Popiel." There's a film from Poland called "When the Sun Was God" that features Popiel as a main character.
Apparently, there is an old ruin in Poland that is called the Mouse Tower and is supposed to be the very tower Popiel was killed in (though historians doubt it.) For more on that structure see The World According to Google and here's a Polish flicker photo of the tower.
During my searches I found this other tale of a Mouse Tower. This time it's a Bishop Hatto on the Rhine who is devoured by rats and mice. Here's the horrible climax to this version:
They were in at last, and sprang at him fiercely.... He beat them off by the score; he trampled them under his feet; he tore at them savagely with his hands–all to no purpose; he might just as well have tried to beat back the ocean. The rats surged against him like waves breaking on a cliff, and very soon the Bishop was overwhelmed in the horrid flood. Little was left to tell of the tragedy when his servants plucked up courage to enter the building some days later.
Here's a Wikipedia entry on that version of the legend.
I tell you, I love this stuff. Half-remembered things from childhood lead down interesting pathways.