I visited all 159 different stations in the metro system, which is operated by two companies:
- TMB runs lines L1 to L5, L9 and L10 (both separated in North and South sections), L11 and the Funicular de Montjuïc (which yes, it's a funicular, but it's fully integrated in the network and TMB treats it just as another line - which it's exactly what it is for all it matters, so I think it should count).
- FGC runs lines L6, L7, L8 and L12 (for the most part, these lines share tracks with suburban and regional services, and I think a station should only count as visited if it is done on the metro services - gotta plan well to catch a good L8!).


I took timestamped pictures of most of the stations and all interchanges in case anybody wants proof, but I won't share them or the route publicly cause I'd love if somebody joined and tried to beat it. I'd say my route is very solid, I was looking for a sub 8 hours for most of the run until I got -very- unlucky in a couple of connections towards the end and suffered some minor delays.
PS. I wish GWR added this big system in this super-well known city to their list of approved records, cause I think I can record for 8 hours with what I have. Anyway, regardless of that, it was a bit tiring but super super fun! Now I wanna do another one....... I travel to Madrid from time to time, maybe try to get the Spanish double crown?
