By 1919, an influx of labor had migrated to Berlin turning it into a fertile ground for the modern arts and sciences, leading to boom in trade, communications and construction. A trend that had begun before the Great War was given powerful impetus by fall of the Kaiser and royal power. In response to the shortage of pre-war accommodation and housing, tenements were built not far from the Kaiser's Stadtschloss and other majestic structures erected in honor of former nobles. Average people began using their backyards and basements to run small shops, restaurants, and workshops. Commerce expanded rapidly, and included the establishment of Berlin's first department stores, prior WWI. An "urban petty bourgeoisie" along with a growing middle class grew and flourished in wholesale commerce, retail trade, factories and crafts.