 In his early works Ullberg used as his basis Nordic Classicism, emphasizing reductive common elements from Classicism.The most important works of the era became Ullberg's reply to the serious social needs of the city.Among these works are the Viipuri Art Museum and Drawing School (1930), the Viipuri Panttilaitos Oy Building (1931), the Viipuri Provincial Archives (1933), and the Viipuri Maternity Hospital (1937).