I am having to do a crash course in Poland Travel. Several have suggested the IN YOUR POCKET GUIDES. I'm not sure why I'm so late in finding out about these online guides, but they are quite helpful. I was going to download and print some of them and discovered there is an App. And its free and quite good. The App allows me to pin the sites I'm interested in and it plots everything on a map. Just about every place I'm hoping to go to in Poland has a guide.
I already make good use of digital travel books from my library service, but honestly this app is much easier to use than a digital guidebook. It is much quicker to find what I'm looking for, and the app is more interactive.
There is quite an interesting variety of places with guides--many are central Europe, but there's one for Dublin, Copenhagen and Aruba!