However, Barcelona is not famous for its flamenco. Though some flamenco acts have come out of the city (Ojos de Brujo being the most famous), Flamenco has far more in common with the south of Spain and Madrid than Barcelona.
Still - if Barcelona is your only stop in Spain, seeing a flamenco show there will certainly do you no harm.
Note: I have never seen any of the flamenco shows on this page so cannot say if they are any good or not.
The people behind Opera and Flamenco have begun a new, more traditional show, entitled 'Gran Gala Flamenco'. More information at their website, Barcelona y Flamenco.
Address: C/Princesa 2
Address: Las Ramblas, 35
Two shows per night, at 10pm and midnight. As with any flamenco show, always see the later showing. This is the one more Spaniards will attend so the performers are more likely to do something 'authentic'.
Address: Avda. Marqués de Comillas s/n. Poble Espanyol de Montjuïc.
Address: Balmes, 139