Even in the most fictional of stories, the setting is allowed to be unabashedly real. The Boston Public Garden is unlikely to sue Robert McCloskey for defamation by duckling, and Ludwig Bemelmans needn't worry that the city of Paris will object to his portrayal of its hospital ceilings as cracked. That means readers get to recognize places they know, which adds some automatic interest to stories. Try reading Make Way for Ducklings to a classroom full of young Bostonians some time.
My parents came to visit today, fresh from their long-anticipated vacation in Italy. They saw places they'd heard about and read about, and the two young Olivia Goes to Venice fans in my care will soon be receiving postcards of locations shown in the book, lovingly chosen by my mother, who read everything from Strega Nona to Angels and Demons in preparation for the trip. I expect that there will be cross-referencing of postcards to illustrations.
I've mentioned before that I'm more of a character reader than a setting reader. It was, therefore, fun for me to receive a book featuring very familiar characters.