When you see photos of people who visited Stockholm, you can be quite sure that most of the time there's at least one picture of the number one photo subject in Stockholm: the golden crown! It's almost like you need your selfie in front of that golden thing to proof you've really been to the swedish capital city. You can find the golden crown on Skeppsholmsbron. The bridge to the island Skeppsholmen. And yes, I would also recommend you to go there. Mostly, because it really is a nice place to take a souvenir-photo of Stockholm. You can see Gamla stan behind the crown and everybody seeing your photo will want to go there too. And also because this bridge leads you to Skeppsholmen, which is my favourite island in Stockholm. There are actually two of those golden crowns. Strangely, you don't see many photos of the one on the left of the bridge (when coming from the city center). At least on your way back from Skeppsholmen, you should walk on the other side. From there, you have a beautiful view to Strandvägen with the boats in the foreground.
So: go and take your crown-picture!