In the 1920-1930s, Polish theatre was experiencing a turn to new comprehension of the practice of stage space organization – the art of scenography was developing. It replaced the practice of creating theatrical decorations for garnishing the play and constituting the background for the action. The new scenography declared itself to be an art of the stage space composing. The development of new theatrical practice was influenced by constructivist spatial and rhythmical perception of environment, which Polish artists were improving in close cooperation with avant-garde architects. A similar approach to the stage design is common for the whole European theatre in the first decades of XX century, however the distinction of theatrical avant-garde in Poland came out as a special reference of the culture to its past and in particular to the romanticism heritage. Polish theatrical avant-garde, which came at restoration of independence time, was developing on overlap of the national myth and new unexplored freedom. Artists of the first half of XX century managed to disengage from the romantic myth only in some measure, but instead of resetting the national heroes and their heritage from the ship of modernity they turned to search for the new forms to embody that matter. The article reviews Polish theatre of the 1920-1930-s in the context of Polish romantic tradition on the one hand and constructivism, promoted by new avant-garde artist collectives – on the other. As an example of integration of two movements, a brief description of the unique project of Simultaneous theatre, created by stage designer Andrzej Pronaszko and architect Szymon Syrkus is given.