Stendal is the main town of the Altmark, the quiet northern part of Saxony-Anhalt where brick Gothic churches and old Hanseatic towns sit between the Elbe and the flat North German plain. It is not a grand German showpiece, but it has enough real substance for a slow day: two surviving medieval gates, a handsome market square, serious churches, and a museum devoted to Johann Joachim Winckelmann, the Stendal-born scholar who helped shape European Neoclassicism.
The old town is compact. Start at the Uenglinger Gate, walk toward St. Mary's Church and the market square, then continue south to St. Nicholas' Cathedral. The best part of Stendal is how much of its medieval status still reads in brick: tall gables, defensive gates, and churches built for a town that once belonged to the Hanseatic League despite sitting far inland.
Stendal is strongest as an Altmark stop rather than a destination for a whole trip. If you are already moving between Magdeburg, Wittenberge, or the Elbe towns, it is a worthwhile day of old-town walking and northern German history.