The small shrines around the city are apparently called capitelli, which is the same word used to describe the capitol at the top of a column. Of course both words derive from the Latin word caput, meaning head from which capital letters, capital cities, the Capitol and more derive. Presumably such shrines were representations of heads and then developed into busts, torsos and full length representations of respected saints. This one has a rusting canopy to keep the rain off the divine heads and is somewhere in the vicinity of Rialto, but on a post lunch dash through the calli in pursuit of a teenager desperately following blue and white WC signs there was no time to get my bearings for the image, though I know it was taken somewhere between Campo Manin and Campo San Salvador.
Even Google Street Map was of new use to me in finding its precise location, though it did tell me there’s a shopping area in the vicinity called Merceria del Capitello. Perhaps this research is going to my head?!