From London Bridge station, it takes approximately 15 minutes walking to reach St Paul's Sanctuary
https://s3.us-west-2.amazonaws.com/travelling-to-st-paul-cathedral/uncategorized/navigating-london-an-overview-to-receiving-from-train-stations-to-st-pauls.html
From London Bridge station, it takes roughly 15 mins on foot to get to St Paul's Cathedral, passing by famous spots in the process