41 Passeig de Gràcia, 08007 Barcelona. In front of "Casa Amatller", next to (Gaudi's) "Casa Batllo". Your guide will be holding a green Walks sign.
The Passeig de Gràcia metro stop, on lines L4 (Yellow) and L3 (Green), is few minutes walk away, but please keep in mind that this metro stop has several exits and that there's a train station with the same name a few blocks farther.
Please meet 15 minutes prior to the tour start time.