The settlement of Wieluń was founded probably in c. 1220 by Duke Władysław Odonic. It was first mentioned in documents in 1282, and probably in the same year it received a town charter. In the mid-14th century King Casimir III the Great built a castle here, which was part of defensive system protecting the border between the Kingdom of Poland and Czech-ruled Silesia. The castle itself was remodelled several times, due to frequent fires and wars. Currently, there is a Classicistic palace in its location.