Located in El Raval, right next to La Rambla del Raval in the city center. look for white metal door.

From the airport:

take the aerobus to either plaza de espaņa o plaza Catalunya where you will take the green metro line to Liceu. A 5 minute walk from there.

Sants (main train station):

Take the green metro line to Liceu then a 5 minute walk.