The article mistakenly refers to Sagrada Familia as the cathedral of Barcelona. It's not. It's a minor basilica, not a cathedral.
I'm curious what "minor" means exactly in this context? I've seen the Sagrada familia, and it ain't small!
A basilica on the other hand is an honorific title granted to some churches by the pope for historical/religious reasons.
An interesting note: Saint Peter in Rome, the most famous church in the christian world is not a cathedral itself as it is not where the pope has its seat, that's actually another basilica in Rome, Saint John Lateran, which makes it the most important church in the catholic hierarchy with the title of "Omnium Urbis et Orbis Ecclesiarum Mater et Caput", or "Mother and leader of all the churches in the world".