The Groningen museum is almost a must do if you happen to be a visitor Groningen. The architecture and design of the museum as well as the location in the middle of the "kanal" in it self is a basis for an interesting discussion. Location is just next to the railway station.
Inside you find varying exhibitions; some thematic others permanent and then again a number of varies over time. Really nice I think. Also, you have a nice cafe where you can get a coffee and cake or a meal.