You can reach Via Vittoria easily in many ways:

BY UNDERGROUND
Piazza di Spagna Underground stop. Turn right on Via del Babuino and proceed for 500mt.
Via Vittoria is on the left.

BY BUS
Line 117 from Piazza Venezia, line 119 from Piazza del Popolo.

TAXI STATION
L.go Gooldoni
Piazza di Spagna