Activity in Barcelona for college freshmen

Girona and Figueres can be easily reached by train. There really isn't any need to involve a travel agent or a tour guide unless the travelers are looking for a specialized tour.

Girona is about 40 minutes by fast train, for which ticket prices vary widely. If you buy soon after tickets go on sale, you can pay as little as €9.40. If you buy on the day of travel you may pay as much as €31. If the travelers want to make last-minute plans, they can choose a regional train that takes about 80 minutes and pay the same price no matter when they purchase the tickets. Those trains are generally much cheaper, but I don't know how the fare compares to the early-purchase fast-train fares.

Trains to Figueres take longer--55 minutes for the fast one up to 2 hours for the regionals. Fares will be a bit higher than to Girona.

I concur with Ann, Girona and Figueres -don't forget also Besalú or Cadaqués in the same area, among other!- are easy DIY escapades.

As per flamenco, note that you're visiting Catalonia, which has its own unique traditions and heritage, among which flamenco is not really included. Albeit there are records of flamenco performances being offered at the Liceu Opera House as well as at the Teatre de Santa Cruz during the mid 19th century, flamenco was really brought to these shores by the successive waves of migrants that came from Andalucia and elsewhere, first during the early 20th century and then in the 60s.

While these days you can find some shows in the city, these are mostly catered for tourists (with probably a couple of exceptions) and it's not something you'd find in our folk festivals or other traditional celebrations. Think of flamenco performances in Barcelona much like country line-dancing shows in say New York -if you know what I mean. Still, there's one exception to this: the Feria de Abril in Barcelona. The large community of residents with ancestry from Andalucía celebrates an annual festival resembling the Feria de Abril in Seville where lots of flamenco dancing takes place... but that'd be.... in April :)

Thank you, guys, very much.
So Flamenco isn't an option then as I am not sure I've seen square dances in NYC.
Any other activities you may think is suitable for 18 years old traveling without parents?
Also the need for the organized tour to Figueres and Girona is quite justifiable:
If we prepay the trip then they will have no other choice but to go there. :)
So still opened to any suggestions

LOL!... that thinking is flawed Lara: they can always claim they "went" :)) Frankly, and without wanting to spoil your good will, college freshmen in a city like Barcelona will surely find many things to do -and not necessarily always as cultural as you'd probably want.

Anyhow, as a general rule of thumb, there's no reason whatsoever to involve travel agencies for visiting anything here as most activities/places -if not everything- can be DIYed: it's far cheaper and immensely more fun. As per safety, a question that often pops up among US visitors, this is a big city with residents from over 120 different nationalities and all sorts of backgrounds, so risk exists of course, however, we don't have a gun or gang problem -in fact, there are none of either- and in general terms it's one of the safest (as in "personal safety") major cities in Europe. Same goes for the rest of the region. Yet it's a city, so if your freshmen come from rural areas, one needs to remind them to be alert and follow basic precautions as, in fact, you'd actually do when visiting any other city, right?

Without knowing likes and preferences it's very difficult to advise, so you could instead have them look at these sites to get some potential ideas:

http://www.barcelonaturisme.com/wv3/en/
http://www.infocatalonia.eu/
http://www.timeout.com/barcelona
http://lameva.barcelona.cat/en
http://www.barcelonaesmoltmes.cat/en/inici

Also, for escapades outside Barcelona, aside of those previously mentioned, these are also interesting (and can be done on public transportation, so no need to rent a car):

• SITGES - a quirky summer destination at a stone throw away from Barcelona
• MONTSERRAT - a nature's paradise:
• TARRAGONA -to admire the glorious past of this important Roman city
• VIC -important business centre from the 4th century BC and through our history to this day
• ROSES - a picturesque town in Costa Brava
• TOSSA DE MAR - another coastal town with a fortified walled centre from the Middle Ages

Finally, here some brochures:

• Welcome to Catalonia - http://act.gencat.cat/wp-content/uploads/2012/08/Welcome.pdf
• Catalonia Experience - http://act.gencat.cat/wp-content/uploads/2015/03/CATALUNYA_EXPERIENCE_EN_DE_RU.pdf

I would also suggest getting a bit of background about the region they're about to visit, Catalonia, as this might not quite be the image you/they might have in mind. Yes, this is politically part of Spain, but has little to do with Spanish culture as portrayed in Hollywood, sorry :))

Enjoy!

I think they should go to clubs, hang on the beach and kiss a Spanish boy or girl. Also lots of beer and wine drinking. That's what I did and it was very memorable.