Situated on the highest mountain of the Netherlands (300m high), is the labyrinth of the drielandenpunt (point of the three countries). I was there yesterday, and can recommend it. It was actually the first labyrinth I've ever been which was a bit difficult. It features bridges, and fountains block your way if you come from the wrong side. So it was pretty fun.
As openstreepmap had a very poor version of its map, I've updated it using Bing imagery and my memory. It should be pretty complete. But of course the whole fun is to complete the labyrinth without looking at the map!