Street sign near the lovely turtle fountain, showing it's in Rione XI - "Sant'Angelo"
The smallest of Rome's rioni, this lies along the Tiber river, east of Tiber Island.
Rioni bordering this district, clockwise from north to south, include:
Regola, Sant'Eustachio, Pigna, Campitelli, and Ripa.
More here.. http://en.wikipedia.org/wiki/Administrative_subdivision_of_Rome