Kalisz's Market Square is the civic centre of the rebuilt city. The square's older fabric was largely destroyed in 1914, so what you see now is mostly interwar reconstruction around the 1920s town hall.
The town hall is still the practical anchor of the centre, and its tower gives a useful overview of the city if open. The square is also the easiest place to start reading Kalisz: a medieval plan, a 20th-century disaster, and a confident rebuild all in one place.