Castle Olsztyn is a dramatic ruin on limestone outcrops southeast of Częstochowa, part of the medieval Eagle Nests chain that guarded routes across the Polish Jura. Its broken towers and rocky setting give it far more landscape presence than a simple village castle.
It is a short excursion rather than a central city sight, but it clearly belongs in a Częstochowa itinerary if you have time beyond Jasna Góra. The ruin is especially appealing in good weather, when the surrounding rocks and views do as much work as the history.