Over the course of quite a few visits to Italy, I have read a good deal about Italian history, art, and architecture. Much of what I learn, I eventually forget unless I use it.
If those things interest you, it would be a waste of a trip without reading this book first: The Art of the Italian Renaissance: Architecture, Sculpture, Painting, Drawing.
It begins with Medieval, and runs through to late Renaissance in the 1600s. Tons of pictures, and very well-written in almost-scholarly detail. Rich in detail.
The authors blend history with cultural history. A great pleasure to read. And how else would you really know what you are looking at?
(It helps to be familiar with the locality's regional foods, too.)