Modena's oldest balsamic vinegar producer (since 1605) is also one of the best and most dependable to visit, with six one-hour English tours daily (9.30am, 10.50am, noon, 2pm, 3.15pm and 4.30pm). While there are more intimate, family-run acetai, slicker Giusti is notable for its explanations of both the strict DOP (Denominazione d’Origine Protetta) process as well as the more industrial (and less coveted) IGP (Indicazione Geografica Protetta) process. Of course, you'll taste.
It's 7km northwest of Modena and reachable by train to Quattro Ville (€1.50), which lands you within 1km, or by bus 500 (€1.50) to Lesignana, which stops 900m away, from Modena's Autostazione.