On which river is Warsaw to be found?

I've not been to the Vistula river

Literally nobody calls it the Vistula in Poland. The proper local name is the Wisła.

When there is only one European river to choose from, the question becomes ridiculously easy.

Choosing between the biggest non-European rivers and an unknown (to me) was easy. Warsaw, Indiana, is not on the Mississippi River.

well, it's not any of the others is it!?