Walk down the main street on the island of Södermalm! From Slussen Station, walk up the hill to Götgatan, and follow it through the pedestrian only shopping area. When the street starts heading downhill again you will past Medborgplatsen (a popular meetingplace with large patios summertime), and then continue along the busy street all the way to the other side of Södermelm. This used to be the main road leading to Stockholm when Old Town was just the Town.
The whole street will take about 30 to 40 minutes to walk from Slussen station down to Skanstull station, and you'll find many restaurants to eat at and stores to shop from along the way. We highly recommend combining this walk with a walk to Nytorget (also on Södermalm) and then back along Katarinavägen to Slussen Station. Katarinavägen offers the view while Götgatan offers shopping, so you can choose what you would like to do first!
APPROX 20 MIN WALK FROM T-CENTRALEN