I don't know what was so special here at Fredfoss but I will strongly recommend you to go there for a visit.
I hope that I wasn't impressed only because the weather was amazing and the situation special. I will only up-load some photos from there and you'll decide if you want to go there or not.
I have to mention that I was one of the participants at the Dresser-Rand User's Conference in 2009, which was itself a good experience and a good occasion to meet nice people and to make good friends too.
I don't know who was the artist who did all those cocoons around in Fredfoss, but he had a beautifull vision abot US.
Instead of taking the spiral road tunnel up to the top of Spirallen, try taking a walk up to the top along the path "Zigzaggen", which winds it's way upto the top giving fine views on the way.
An added attraction of taking this route is ?spaviljongen or "the pitstop", which is located roughly halfway up the hill.
?spaviljongen functions as both a bar to those making their way up to the top but also as a fine restaurant in it's own right.