midnight mass in barcelona?

Hi Jen
Sorry to disappoint you but we Catalans are not a religious society -in general terms that is. This is not to say some traditions aren't still maintained, but more as such rather than out of religious devotion (Some info: https://www.barcelona.cat/en/christmas). Obviously, there are fellow citizens that are religious but go to any mass on any given Sunday in most towns and cities here in Catalonia, including its capital Barcelona, and you'll be rather surprised to see the low attendance in relation to the population of the place. The Spanish are, in general, much more religious than us Catalans, and in places like Seville, Cordoba, even Madrid, you'll stumble upon plenty more people in mass or in other religious celebrations.

Having said that, if you're in town on the 24th, you might want to attend the Missa del Gall (mass) which commences at midnight (or a bit earlier in some churches). One of the most popular (=crowded) ones is the one in the Cathedral, in the Old City. Also, a bit earlier you can listen to the Cant de de la Sibil·la, a liturgical drama and a Gregorian chant, the lyrics of which compose a prophecy describing the Apocalypse, which has been performed, in Catalan language, at some churches across the territories of the Països Catalans on Christmas Eve nearly uninterruptedly since medieval times.

Enjoy!

That will certainly be quite a show.

For an alternate idea, in the Eixample take a look at the Basilica of the Immaculate Conception.
The RS guide and google maps still call it an eglesia/iglesia but it was promoted/upgraded by the pope a few years ago to basilica status, and it has a great men's choir.

I think this is the one I'm recalling:
http://www.parroquiaconcepciobcn.org/ca/inici

... or, if you're reaaallly in the mood for a one-of-kind experience, you might want to rent a car for an escapade to Montserrat on the night of the 24th and attend the Missa del Gall in the abbey. You'll be able to enjoy the performances of one of the best boys' choir in the world, l'Escolania de Montserrat: https://www.ccma.cat/tv3/alacarta/missa-del-gall/missa-del-gall-2012/video/4399851/ in one of the strangest landscapes imaginable, the mountain of Montserrat: http://infocatalonia.eu/w/Guw7G

... also, worth mentioning the Live Nativity in Corbera de Llobregat, a town merely 40km from Barcelona that you can reach by bus or by train in an hour or so: http://pessebrecorbera.cat/ The live nativity is a half-a-mile long itinerary in a superb natural landscape portraying different scenes related to the birth of Christ, with over 200 actors and yearly performances since 1962. If you're interested hurry up to grab tickets!.... http://pessebrecorbera.cat/preu-entrades/?lang=ca There are only 7 performances.

Thanks for sharing that link to the mass in Montserrat, Enric.
It's a great way to get our ears attuned to the Catalan language.

As a side-note on the language, the famous novel "Woman Warrior" by Maxine Hong Kingston is now available in a Catalan translation, and I was at a book club event with the author where she asked for a "Spanish speaker" in the audience to volunteer to come up to the podium and read the opening lines -- a Chicana came forward and took the copy from Maxine's hand, flipped to the first chapter, and said, with embarrassment, ~I don't think this is in Spanish, it looks like French maybe?~ --- it turns out that the author didn't know that it was not a Spanish edition but a Catalan edition, La Dona Guerrera.