Complex sentence: In the interbellum period Lviv held the rank of Poland's third most populous city (after Warsaw and Łódź) and became the seat of the Lwów Voivodeship--after Warsaw, it was the second most important cultural and academic centre of interwar Poland.
Split into simpler sentences: In the interbellum period Lviv held the rank of Poland's third most populous city (after Warsaw and Łódź) and became the seat of the Lwów Voivodeship. Its geographic location gave it an important role in stimulating international trade and fostering city's and Poland's economic development.Right after Warsaw, it was the second most important cultural and academic centre of interwar Poland.