Where to experience the real Serbian culture?

I mean the places in Serbia where you’ll go and see the real culture, food, people, architecture… I mean places as in cities or some smaller towns as well. Or something that will leave me in “wow”?

Ok Belgrade is the city I’m aware of but I guess many tourists visit it. And I figure it might be mix of modern things since its capital but what about other places?

Are people in smaller towns even friendly and open to new people?

Thanks ^