I hava family in Sweden, and have been to Stockholm a few times. Usually I’m just travelling through, but I’ve also been doing other stuff within the city.
One of the most interesting was a cow-chasing trip on bike (cow statues were located in the city, and through a map the goal was to visit as many as possible of them). I did this with other family members, and got myself a nice tour of Stockholm. I believe that was in 2004, but not sure.
I believe the cow statue thing was a travelling thing, visiting other cities at least within Europe. Perhaps you’ve seen them too?