This is not true. Industrialization began in Eastern Europe (With the exception of Russia). Poland, or at least the occupied territory of Poland, had a number of industrial boom towns that grew rapidly beginning in the latter half of the 1800’s. The Case study for this would be Łódź–where the population grew from 3 peasants and a goat to 800,000 over 50 years. The rapid growth is marked in the city by the preponderance of buildings in appropriate styles of time as well as large numbers of 2-3 story workers housing. The Workers housing complexes are most interesting in that the buildings featured a wide range of non-structural features in brick, incluing false crenelation and ornate edging. There are many many buildings in the eastern style of Art Neuveau, Deco, Streamline Moderne, etc reflecting the growth of the city during those periods as well. Łódź not alone in this development pattern, though it is perhaps the most striking example of it, and the country is heavily marked by industrialization by a wide array of buildings expressly built for the workers featuring quite a bit of ornament. It is specfically those buildings built during the communist era that are locally most famous for a complete lack of ornemant, bland floor plans, and a total disrespect for the fabric of the city that came before.
Which isn’t to say that the process of urbanisation didn’t continue under the rule of the communists: It did. But it began and and had its heaviest periods of migration well before they showed up.
