Ivar Los park lays a little hidden, but is a super cozy little gem with great view over Stadshuset (the town hall), Kungsholmen, Gamla stan and Mälaren. It has a charming old-time feel to it, with the red tree fence and the massive ash tree.
It is the perfect place to take beautiful pictures and rest your feet at the same time. In the summer it is a perfect place to just hang out, have some food and a beer. In the winter it is a popular place to go sledging in the snow.
See if you can find the hollow ash tree.