Passage: Nevertheless, underground organizations and individuals – in particular the Polish Underground State – saved much of Poland's most valuable cultural treasures, and worked to salvage as many cultural institutions and artifacts as possible. The Catholic Church and wealthy individuals contributed to the survival of some artists and their works. Despite severe retribution by the Nazis and Soviets, Polish underground cultural activities, including publications, concerts, live theater, education, and academic research, continued throughout the war.

Question: What was the name of underground organization that saved many cultural works?
Polish Underground State