None, perhaps Spagna. An alternate is to take Bus 40 or 64 (get off at Piazza San Panteleo, 2 stops past Piazza Venezia, then walk a half-block north from there).
about 5 minutes
Viewable at any time
The fountain of Via della Posta Vecchia is a cute little fountain built in 1872 located on the tiny north-south street Via della Posta Vecchia, which is between Piazza di Massimi and the southeast corner of Piazza Navona.
A small wall decoration above and to the left of the Fountain of Via della Posta Vecchia, perhaps indicating that the Column in Piazza de Massimi is nearby in this direction (?) See all Fountain of Via della Posta Vecchia photos.