We tried and failed to get up to the top of Tibidabo at sunset (the funicular's last ascent was at 4:45). We were exhausted from having walked up to the funicular instead of taking the bus (a nice walk except I was wearing shoes made more for fashion than for comfort). So we ducked into one of the places perched on the side of the hill near the funicular station.
What we didn't know is that Mirablau is one of the hottest discos in Barcelona. However, at 5pm, it looked just like a regular bar with a really stunning view of the city. They have a wall of windows facing the city below; at sunset, it was beautiful and romantic. Our expat friend told us that in the warmer months, there are no windows--just fresh air and the view. It is well worth the trip up to watch sunset from this place. We didn't make it back to the disco, which I assumed got going around midnight. It would be a great place to dance the night away, though.