The Mouse Tower is a custom tower on a small island in Rhine in Germany. It was built originally by the Romans. Local legend says that the tower was used as a custom tower by some greedy local bishop (Hatto) who oppressed and exploited the peasants in his domain , collected a tribute from the passing ships , and killed crews who did not pay the tribute . But one day the tower has been attacked by huge army of mice . Those rodents ate all available food first and the bishop himself next .