El Xampanyet has been on Carrer de Montcada since 1929. The bar does not look like it has changed much. Tiled walls, a long zinc counter, bottles stacked behind, pintxos under glass. It is loud in the way that a bar is loud when everyone in it is having a good time. You will need to push in a little to get served. This is fine.
Stand at the bar. Order the house cava. You're in Barcelona now.