Trains run two to four times an hour from Venice’s Santa Lucia station; it’s 30- to 40-minute trip, definitely your fastest option. Tickets start at 3.45€ one-way. Arriving at Treviso Centrale station, you’ll have an easy 10- to 15-minute walk to Piazza dei Signori, north across the River Sile (follow signs to “Centro”). Note also that most Ryanair budget flights to Venice actually arrive at Treviso airport (p. ###).
From Venice, the quick way by car is Autostrada A27 to the Treviso Sud exit, but the more direct route is the SS13 (though that can be slow going at rush hour and midday). From Padua, take Autostrada A4 past Venice to the A27.
The tourist office at Via Fiumicelli 30 (www.visittreviso.it; tel. 0422/547-632) is open Monday from 10am to 1pm, Tuesday to Saturday 10am to 5pm, and Sunday 10am to 4pm.