The construction of the museum's contemporary New Main Building located at 3 Maja Street, started in 1934, but was interrupted by World War II.

[1] The collections – consisting of several hundred thousand items in total – are kept in big part in the Main Building where the administrative offices are located, but also in the nine of its divisions around the city.

[4][5] The Main Building features the newly renovated upper Gallery of the Twentieth Century Polish Art, one of the largest galleries of painting and sculpture from the late 19th century on in Poland, with most celebrated artwork by Jacek Malczewski, Leon Wyczółkowski, Włodzimierz Tetmajer; an extensive collection of works by Stanisław Wyspiański; and also, works by artists of the interwar and postwar periods: the Polish cubists, expressionists, colorists, the avant-garde of the 1930s, and representatives of New Directions from the 1960s.

[1] Paintings in the collection include masterpieces of the Young Poland movement (Konrad Krzyżanowski, Olga Boznańska, Józef Pankiewicz, Władysław Ślewiński, Wacław Szymanowski, Ludwik Puget, Jan Stanisławski, Tadeusz Makowski).

Decorative arts and crafts are exhibited in the Decorative Arts and Crafts Gallery, with gold, silver and precious stone artifacts ranging from twelfth to eighteenth century; copper, pewter and iron objects, such as bowls and wrought iron chests; old furniture, musical instruments, clocks, ceramics and glass, notably stained glass from the churches of Kraków.