Where was Zhenya, Zhenechka and Katyusha filmed?

1967 film by Vladimir Motyl

Zhenya, Zhenechka and Katyusha (1967) was filmed in Kaliningrad, Peterhof, Vsevolozhsk, Königsberg Cathedral, Yantarny, Königsberg Castle and 5 more places, 11 places named in its Wikipedia article, in Russia. Wikidata records no filming location for it at all, so the article is the only recorded source. Each place says where its claim comes from.

See them on the map → Wikipedia Source data