I used to navigate Italy as a tourist using the three green volumes of the Carta stradale d’Italia (1:200,000), whose detail included passages that could barely be driven by a rental car. There are since map series at 1:50,000 and 1:25,000 [1].
I found this post title "Italian streets that don't exist on any map" misleading, given my experiences there. The article describes fictitious streets.