When I read the description of Wanda Jakubowska’s film The Last Stage (1948, Ostatni Etap in the original Polish), I couldn’t quite believe it: a feature film, set in Auschwitz-Birkenau, filmed on the grounds of the former concentration camp in 1947, written and directed by former prisoners. I saw it at the 2020 Berlinale, where a newly restored version was making its world premiere.
Source: The Last Stage: a masterpiece of early Holocaust cinema | Sight and Sound