Barcelona's cultural roots go back 2000 years. To a greater extent than the rest of Catalonia, where Catalonia's native Catalan is more dominant, Barcelona is a bilingual city: Catalan and Spanish are both official languages and widely spoken. The Catalan spoken in Barcelona, Central Catalan, is the one closest to standard Catalan. Since the arrival of democracy, the Catalan culture (very much repressed during the dictatorship) has been promoted, both by recovering works from the past and by stimulating the creation of new works. Barcelona is designated as a world-class city by the Globalization and World Cities Study Group and Network.

  The Barri Gòtic ("Gothic Quarter" in Catalan) is the centre of the old city of Barcelona. Many of the buildings date from medieval times, some from as far back as the Roman settlement of Barcelona. Catalan modernisme architecture (often known as Art Nouveau in the rest of Europe), developed between 1885 and 1950 and left an important legacy in Barcelona. A great number of these buildings are World Heritage Sites. Especially remarkable is the work of architect Antoni Gaudí, which can be seen throughout the city. His best known work is the immense but still unfinished church of the Sagrada Família, which has been under construction since 1882, and is still financed by private donations. As of 2007, completion is planned for 2026.

Barcelona won the 1999 RIBA Royal Gold Medal for its architecture, the first (and as of 2007, only) time that the winner has been a city, and not an individual architect.