Zawodzie Archaeological Reserve marks the early medieval heart of Kalisz. The site reconstructs parts of a Piast-period stronghold, including palisades, a gate, a bridge, timber buildings, and traces of the collegiate church that once stood here.
It is the one sight that makes Kalisz feel genuinely ancient rather than merely old. The reserve sits about two kilometres south of the centre, so it is best treated as a deliberate stop, not a casual detour while walking the old town.