Rione XIII will be on 15th Ave East at the corner of Harrison - the Stranger food guide has the address without the "east" so it maps to 15th & Jefferson.
Will. Regioni were the ancient (Augustan-->medieval) divisions. It's Latin. Rioni (Italian) are the Renaissance-->modern non-administrative divisions of the old central city. (The still more modern administrative divisions of greater Rome are the municipi.)
You mean Regione? That's like Quartier in Paris (Quarter), or Arrondissement (Borough, or "section around a center").
Hard to mess up vodka.
It's right there in the restaurant's logo.