The courtroom in which Valery Legasov, Boris Shcherbina and Ulyana Khomyuk tell the truth about the Chernobyl accident (episode 5) was filmed on the second floor of the Tyszkiewicz Palace. It now houses the Faculty of Architecture of Vilnius Gediminas Technical University. On the top floor there is a large assembly hall, which has miraculously retained quite an authentic soviet-style look.

Screenshot: HBO Chernobyl (2019)