Pod Zamkiem — "Under the Castle" — sits at the foot of Sielecki Castle, which is the most reliable address in Sosnowiec for traditional Polish cooking done properly. The menu covers the Silesian classics: żurek in a bread bowl, roast pork knuckle, pierogi, bigos with smoked meat. Portions are generous and prices remain firmly within the range that locals actually use, not the tourist-adjusted prices you find in Warsaw or Kraków.
The setting, in a building that shares the castle grounds, gives the place an atmosphere that other Sosnowiec restaurants don't have. Go for lunch — the midday set menu is the best value.