From road ring (big shopping center with lots of parking spaces) to Vatican city.
The nicest part in skating through park near Villa Borghese.
http://www.gpsies.com/map.do?fileId=wdiplltgokfxeurq
embedded map:
kml file: rome-from-ring-road-to-vatican-city.kml
And some random video from youtube. Not this path, but you get the point.