 The most interesting examples from this period include the reconstruction of the Union Bank (originally built in 1900), the Karjala offices (1929), the store and residence of V. Dippel (1921) and the restoration of the famous medieval Round Tower in the middle of the old city centre.Ullberg converted the massive old building into a restaurant and cafe.The most important period in Ullberg's architect career is connected with the "White Era" of Functionalist architecture.