The Casa Golferichs is a Modernist house built in 1901by Joan Rubió i Bellver, one of Gaudí's collaborators. It was commissioned by Macari Golferichs, an exotic wood trader (the mind boggles) and you'll find it on the corner of Gran Via and Carrer Viladomat.
I happened to be passing by on a holiday so it was closed. However, since the 1980s it's been a Centre Civic - Community Centre - so if you happen to be in the area on a working day, you'll have no problem getting inside.
The next time I'm in the area I definitely plan to check out the apparently sumptuous Modernist interior.