The Town Hall stands in the middle of the Market Square. It was built in the years 1824-28 thanks to the patronage of Prince Antoni Radziwiłł according to the design of J. H. Haerbelin, an architect from the circle of Karl Friedrich Schinkel. During the reconstruction in 1862, the passage through the inner courtyard was closed. Reconstruction after the war damage, completed in 1948 and carried out according to the plans of architect Kazimierz Ulatowski, completely changed the appearance of the building. Renovated in 1977-87.
It is a three-story building, built on a square plan with a small internal courtyard, secondarily roofed. The flat roofs are covered with an attic decorated with pinnacles. The façade is dominated by a turret with a pseudo-baroque dome and two lanterns. The clock with a chime inside comes from the second half of the 19th century. 19th century. Below the clock face there is the city's coat of arms. The facades - decorated with rustication on the ground floor - are crowned with a prominent crowning cornice. The main entrance leads through an arcade supporting a balcony with a stone balustrade. On its sides, on the facade wall, there are two plaques commemorating the liberation of the city from Nazi occupation and the fights of the Home Army units.
Inside there is the Ostrów Wielkopolski City Museum and the Wedding Hall.