The best thing about the place is it is a museum and aquarium. There is something for everyone. Animals, touch it tank, history, interactive exhibits about ecology and science, a paddleboat dredger to go on, other boats to look at and visit, huge outdoor area for little ones to get their energy out, a small nature trail with some historical exhibits amongst the plants and waters, and an affordable gift shop (very rare on vacation). So if you have some kids who love animals and others who love history, and some who love other sciences, this place will keep everyone happy. If you are in the area, well worth a membership -- it pays for itself quickly, especially since it gives you a 'go to' place in the cold Midwest winters. You can't miss this if you are in Dubuque for any reason. You learn something new every time, and the people who work there are tops!
I will admit, after having spent my whole life travelling and living only in huge cities, I expected a dinky little place. I was so wrong, about this place, and Dubuque.