I wasn't aware of the existence of this city until I had to book a ticket from Barcelona to Moscow. Many ticket aggregators showed a few very cheap options, but they also showed warning icons nearby them, informing me that a departure airport is not exactly in Barcelona but in Girona, a little town nearby. That was the first time I heard about this city, and I decided to spend a few nights there before coming back to Moscow.
I've heard a lot of good things about Barcelona and I have always wanted to visit it. My trip to Barcelona started rather unexpectedly, I just wanted to get a Schengen visa and I was advised to pick Spain as a country of first entrance because Spain tends to issue longer visas which can be re-used later to visit other EU countries.