Las Ramblas is a really cool and living street but watch out for pickpockets. Yup, this is the perennial tourist trap. Lots of interesting things to buy and see but be very very very careful about your belongings and NEVER EVER go here at night. It is simply too dangerous.
Be careful with handbags, this only really applies to ladies. I was told that thieves were rife in Barcelona. So just keep it tight to you and always have compartments zipped up.
Also be very cautious of women giving out flowers. I was given a rose and thought nothing of it, however the woman wanted money for it and when i said no and gave her the rose back she got angry. She started throwing stones and shouting, this is was in a busy main street as well.
Like tourist sites anywhere in the world watch out for thieves. They will literally steal items off your table while you are eating so make sure your camera and such are attached to your body in some manner.
The biggest single danger is street crime, coming mostly in the form of theft of your valuables. Luckily, I've not had the problems myself, but I've seen it happening. Generaly, somebody will just grip your bag and run away with it, but some people I know have noticed more 'remarcable' performances by the criminals.
National Museum of Art in Barcelona. No warnings or dangers in Barcelona, except one very dirty looking guy following me some distances when I was walking to a park. I don't know what he wants but I think he wants money, the problem is why he choose me ? because I was as dirty as him and I don't look rich at all, can't understand.
Don't fall for fake tourist with maps. It almost happened to me. I was just about to help this little guy but then I noticed two big guys approaching. They were trying to surround me but In the last seconds I managed to escape.
Also there can be some nomal guys acting as civilian cops and asking for your passport. Don't show it for nothing because they are just trying to steal your valuables at the same time.
Swindle and steal is the everyday's job for this people! Their name is 'trileros'. One of their prefer places is in 'Las Ramblas' or 'Plaza Catalunya' where they are trying all the day make a deceit to pedestrians: specially tourists!!! What's the way to do it? Really easy! They are groups and they do a 'timba' that is a table make with cardboard, and hide a ball inside 3 boxes. Obviously, each person in the group has their function: vigilance, 'hook'...the main objective is tempt people to do a bet!
Pickpocketing. Beware it. Assume someone's always casing you, because someone always is. keep your purses zipped shut and in front of you. Keep your wallet in a place you can check constantly such as a front pocket. Chains are a good idea as well. NEVER leave anything unattended unless you WANT it to disappear forever.
Oh, and guys: do an Adam's Apple check on that beauty you just met. Barcelona IS the transvestite capital of Europe.
You only need to be careful of pickpockets in places with lots of tourists (train stations, beaches and so on...)
It's certain Barcelona has become a bit unsafety city during last years. But it's a problem which have all large cities in Europe: Madrid,Paris, Amsterdam...
So don't worry.
On the other hand,it would be good you take care of our beaches and monuments when you come here,too.
If you respect all them,next tourists can see it in a good status.
As in any city, in any country, you must always beware of thieves. Pickpockets operate in all areas frequented by tourists, especially at Las Ramblas, and Temple Familia. Be sure to carry your money and passport inside your clothing (I wear a money belt) and carry your purse and camera snug against you. Don't be too paranoid, just aware! Also, the group I was with did run into a potentially frightening situation. We were there during some major football (soccer) matches, which people in Barcelona are very passionate about. Some of my friends tried to join in the street festivities after a victory, and they were treated with some hostility. This could have been an isolated incident, but never-the-less, be wary.
Beware of Flashers!! we encountered one on this side street... Ok and one thing that is not so nice that I just have to mention about was the men, especially italian. If you look at least remotely scandinavian, in a night club you won't get a moment's rest from them trying to grab your ass and out on the town the looks and the comments. Not all scandinavian women are nymphomaniacs... And I really don't like to be grabbed without my permission!!! There!!
Be wary of little ladies clipping unasked-for carnations onto your clothes or bag while you are occupied with taking pictures. They'll be wanting to get paid for it and won't let you go before you do. Not a major danger, but annoying just the same. We ran into them near the Sagrada Família and it stands to reason they can be found near other major attractions as well.
After arriving in Barcelona, we went to a very seedy but quaint bar that is situated on the corner of a building. You stand on the sidewalk and order your alcohol and tapas and drink right there. Most of the people there were just unemployed or blue collar joes that were very friendly. One person offered asked me if I needed 'Charlie', and I said I didn't know him. (Turns out he was trying to sell me coke, he realized that I wasn't much of a drug user and thought that was cute.) We saw one woman who had just been robbed around the corner come screaming down the alley, among some other very interesting things.
The locals turned out really liking us, and one of the locals drew us a map with the right side of La Rumbla, closer to the waterfront, shaded. She spoke no english, but made it clear that we should not go there. There were some guys in our hostel that were not so lucky as to get that message and were pretty badly beaten and robbed. There are plenty of pickpockets, muggers, and pushers around La Rumbla, so be very careful. You will be OK if you stay streetwise. Don't let that detract you from going, just be careful.
Beware of those Roumanians who show you off their passport turned inside out, stating they are 'Tourist Police', and only want to check if you have enough money that satisfies the 'regulations'. They will rob you! They count your money and give it back, but ALWAYS give back less!
The same trick they use in Hungary/Budapest (and maybe all over Europe), so don't be fooled!! (No, I wasn't :)
The girls in Barcelona are not any better than in your hometown !!! :-)
BUT ....they are in Barcelona !!!! :-)