It is located in the centre of the Old Town marketplace and was built as the seat of the Olsztyn authorities. The Gothic part of the building, i.e., its south wing, is one of the oldest relics in the city.

This part was built around 1500, probably in the place of the former seat of the members of the city council, which, in turn, was built in the 2^nd half of the 14^th century, after granting Olsztyn town privileges. Although the new building was burned during the fire of the city in 1620, it was soon reconstructed (1623-1624). This dramatically changed the looks of the building – its dimensions were extended and the tower was added. Now, the building presented features of Baroque style. The basement and the ground floor were turned into a market hall. Another reconstruction took place in the 18^th century.

In 1825, the city hall was the seat of the court. However, the needs of the court were constantly growing. As a result, the city council had to move from its premises for many years. Even a second wing built between 1858 and 1859 was taken by the court.

Only when Oskar Belian was elected the mayor a new premises for the court were built. The city council returned to the city hall in 1880 and remained there until 1915. In this year, a new city hall (on the present John Paul II square) was built.

The building was taken by the Trade School and the Urban Library. The latter was also situated in rooms in the third, northern, wing, which was built between 1927 and 1928. The inner yard was closed by arcades. During the Nazi rule, the building was Hitlerjugend headquarters.

After the city was taken by the Red Army in 1945, the Old City Hall was burned. The building was rebuilt between 1946 and 1949, but it lacked the tower and other characteristic architectural elements. These were restored only during the general overhaul between 1996 and 2003, when the façade of the southern wing was given the features of the Gothic style. After a layer of plaster was removed, red brick walls were discovered. These were ornamented with genuine late-Gothic ogee arches.

The Old City Hall, in its present form, is a three-wing building with a yard closed by arcades and topped by a glass, pitched roof. All the wings are two-storey. The southern and the northern ones are topped by a pitched roof. Moreover, these wings have utilitarian attics as well. Sundials placed on the façade of the southern wing especially attract tourists’ attention. Nowadays, the entire building is taken by the Voivodeship Public Library.