What Is The Longest River In Italy

There's an article on the site (this site) about the river Po and the Po Valley.
Po is a really long river and at the widest point it measures more than 500 meters! I'm curious where that is, I can't find this information anywhere! I'll keep looking.

Oh, and the Po Valley is so beautiful! There are some places where the landscape is so pretty, I could stay there forever! Just look for some pictures on Google Images, you'll see what I'm talking about :P