This is amazing, seems really detailed and leveraging official sources too, nice job!

Since the author seems to be Catalan, I'll shamelessly plug a Metro-station-relevant event that is ongoing right now in Barcelona:

There are many "ghost" metro stations in Barcelona that been popular (at least used to) urban exploring destinations. Two of those, Gaudí and Correus, are now opening to the public via tours, if you register at https://obrimelmetro.cat

I've only visited Gaudí in a unofficial capacity like a decade ago, and haven't yet done the new tours myself so can't vouch how interesting they are, but seems there are only 5000 open spots in total. It seems like one of the tours is even during the night, so you get as close to the urban exploring experience as possible without having to run across active train tracks :)

Thanks for sharing. London has these permanently, and while not cheap, they're very much worth it too.