The monumental building designated for the post office was built in the years 1886-1887 at the current Pieniężnego street, formerly Wilhelmowskiej street. Its creation was to meet the needs arising from the rapid development of the city and the new demands on the postal service, which became responsible for both the telegraph service and the telephone network. The simple but stylish silhouette of the building is a reflection of the past “official”  architecture. This representative, two-storey, red-brick building was given a Neo-Gothic character. The decorative details on the facade, which had to bear its prestige, were added as it was built for the purpose of a public office. The interior of the building is not impressive since already at the design stage its functionality was prioritized. After 20 years of its establishment, the post office was expanded. In 1928 it went through a bigger modernisation, during which a side wing was added. Currently, the building still holds the original function as the seat of the main post office in Olsztyn.