I know that this is taken somewhere from across Vistula river. But can you tell me from which location I should try?
Looking at the buildings - to have the Novotel (blue-lit building) to the left of the Palace of Culture, and in front of the big pointy building (I don't know what that is!), it would need to be taken almost due east of that group of buildings - putting it on the beach just north of Most Łazienkowski.
I am almost sure, that this photo is taken from Siekierkowski Bridge