It's not in the vatican (becuase the state's quite small and impractical, but here's a circuit that's right next to it).
Linked as a Google maps route,
https://www.google.co.uk/maps/dir/41...!1m0!3e2?hl=en
Anticlockwise in terms of the direction. Where the roue goes to a footpath, I'm using the road next to it, and I'm using the higway instead of the chicaney bits at the west of the image.