Barcelona, to be exact. For a week, for business. But still – Spain!
So . . . what do I need to know?
Do NOT try to spend the night sleeping on the ground outside the main train station, unless you want to be knocked unconscious and robbed of all your posessions.
Sweet, I’ll be keeping an eye on this thread, because I may be going to Barcelona in August.
No sleeping outside train station. <check>
Serrano ham
Machego cheese
Tempranillo wine
Aw hell, just eat and drink whatever they give you. You can’t go wrong. 
Street scams of Barcelona. It’s fun reading regardless.
Barcelona is part of Catalunya, and most of its residents consider themselves Catalans first, Spanish second if at all. Their first language is Catalan (a Romance language which superficially resembles a cross between Spanish and French but is actually closest to Occitan), although they all speak Spanish as well.
They are lovely people and it’s a beautiful city. Enjoy.
You might profit from KarlGrenze’s thread What to do in Barcelona?.
And as long as you aren’t from Madrid, they will speak Spanish to you, if you know it. 
But at least try a few words of Spanish if you can.
Expect everything to be closed from 2-4 pm, including stores and banks, so if you need something, get it before siesta or after.
For lunch, buy a loaf of bread and some cheese and fruit and just walk–along Placa Catalunya or Barri Gotic (apologies for wrong spellings; it’s been over a decade.) Oh, and when I was there street signs were all in Catalan but on the maps they were in Spanish. Hopefully they’ve gotten this straightened out; if not, it takes some getting used to. Go to Sagrada Familia and Parc Guell.
The subway system is pretty easy to follow so you shouldn’t have trouble getting around. Also the center part of the city is all in a grid, so walking is pretty easy.
And have a good time. It will be very hard not to!
I just got back from Jerez in the southern region; so whatever you do, even if you think you won’t like it, try some sherry. With a sweet dessert have a Pedro Ximenez or an Oloroso. Spain is the only place in the world where sherry is made, so where better to experience it?
Just an add on to Jeevwoman’s post, when I was in Barcelona last summer, it was really only smaller shops that closed. I didnt notice the banks closing, thats only because I wasnt using them though. Most of the big department stores stay open.
Make sure you walk down the street called Las Ramblas, spelling may be off, its where all the street carnivals take place, and its just a fabulous part of Barcelona.
When I was there, we got on one of those Buses that takes you around all the sights of Barcelona, you buy a day ticket and you can get on and off as much as you like, its a great way of seeing the sights as most major sights have a stop right outside them.
Barcelona is a fabulous city, enjoy it!
We loved Barcelona!
Must see- Sagrada Familia, the Gothic Quarter, every bit of Gaudi you can find! We also enjoyed a mass in Spanish at the excellent Gothic cathedral. I’m not Catholic, we don’t speak Spanish, but it was lovely for us and the two nuns in front of us!
Food- screw official meal times- just wander up and down the ramblas noshing tapas!
Enjoy! I can’t wait to go back!
The Picasso Museum is a must. And have fun!! (although it is true that Barcelona is crime-ridden - but no more than London or New York)
Yea, I was going to mention the thread…
Check the weather. I went expecting sunshine, it rained half the time and the other time it was cold for me.
It’s a beautiful city, I loved it. Park Güell and Montjuic parks have great views of the city.
There are many museums and places to see. I liked La Pedrera (some of the exhibitions are free to the public) and Caixaforum (most of the art exhibitions are also free). The Picasso museum and the Joan Miró museum were also among my favorites.
This year marks the 100th birthday of Dalí. Go check the Dalí exhibitions around the city, particularly the one in Caixaforum, which covers all his periods.