Wolin

An island (though you might missed that fact, as it's connected with bridges) on the Baltic with an interesting history. It had the largest Viking town around the 10th century, later it was a base for mixed Viking/Polish pirates, during WWII Germans used the place to develop their wonder weapons. Also a large protected area with various ecosystems that attract birdwatchers. And resort towns at the sea. I generally avoided vacations at the seaside (why stop on the shore when you can go sailing), but they're unavoidable with a child, so at least I chose interesting places.