Where can I obtain a certificate from the National Criminal Register (certificate of clear criminal record)?
At the headquarters of the National Criminal Register Information Office at ul. Czerniakowska 100, 00-454 Warsaw, or at one of the National Criminal Register Information Points.
The list of National Criminal Register Information Points is available on the website https://www.gov.pl/web/krajowy-rejestr-karny in a tab "Materials to download".