hi, I'm from the Netherlands, and I would definetly recomend themepark 'De Efteling'.
This themepark has a fairytale-forest full with Western-European fairytales and old folklore-stories, rides based on old Dutch mythes and folklores such as the Flying Dutchman, a typical old Dutch square based on the drawings by Dutch designer Anton Pieck, and many magical places not compared to any culture, but just beautiful to see nonetheless.
If you have only one day to see the Netherlands, learn it's mythes, fairytales and folklores through haunting rides and dreamily attractions, is my suggestion.