what to do (with children) (Warsaw)

Hi

my name's Paolo, I've recently moved to Warsaw for a few months assignment. Happy to see that there's a good internations community round here.

I have a question for those who have good knowledge of this town: in february my wife will join me for a week with childrens (from 3 to 7 years old). Does anyone has an idea on what they can do during the week (apart from staying at home of course) with -20° and icy snow in the street? Any special activities or places they can go?

Thanks everybody and see you around

ciao
Paolo