Prior to my visit to Barcelona, I did some research on the best supermarkets for affordable…read moregrocery items. I'd heard about €10 cups of yogurt (something like that) & wanted to make sure I DIDN'T end up at these supermarkets.
Our host did warn me that shopping at Mercadona would be "tricky". I wasn't sure what he meant until I went there myself. Prior to Mercadona, every supermarket I'd been to in the Americas & Asia had more or less been the same in terms of structure/system. At Mercadona - at least the 1 I went to, can't remember anymore which 1 it was - I noticed customers queueing up at the cashiers near the entrance with their merchandise, but the merchandise was nowhere to be found. Hehe.
So I followed this guy to the elevator, & the elevator took us to the second floor. That's where the merchandise was. As I lined up to pay for my purchases, 1 of the workers asked me something (in Catalan). I said I didn't speak the language, & he asked me if my car was parked in the basement. I said no, & he directed me towards the line where I should be paying for my stuff. So I take it some Mercadonas are structured this way, I guess that's just their own system of organization.
Mercadona did happen to have everything I needed, & offered them at good, affordable prices. I'd be happy to do my grocery shopping here again, next time I'm in Barcelona.