If you're planning a fairly short trip to Spain, and haven't the time to go everywhere, then you'll have to answer the question: Madrid or Barcelona? I tend to respond: Barcelona.
In many ways, you will find Barcelona quite different from Madrid, Seville or any other urban area in Spain. Its origins date back more than 2,000 years, before the Roman Empire ruled the Iberian Peninsula.
Even before King Ferdinand and Queen Isabella unified the country of Spain, Barcelona had become the capital of Catalonia, a nation which spoke Catalan, a Romance language related to but different from Spanish. For much of the 20th century under Spanish dictator Franco, the Catalan culture and language were suppressed, but today Catalonia is one of democratic Spain's autonomous regions, Barcelona still proudly holds the status of its capital and the culture is thriving.
All this heritage and history leaves an enormous amount for you to explore. Start with the excavated Roman walls and the medieval old quarter, called the Ciutat Vella (Old City) or the Barri Gotic (Gothic Quarter). You'll marvel at Gothic churches such as La Seu (the cathedral) and Santa Maria del Mar, as well as the Llotja de Mar (chamber of commerce), the Drassanes (medieval shipyards, now a museum), Palau Real (Royal Palace) and its Tinell, the hall where King Ferdinand and Queen Isabella received Christopher Columbus on his return from the New World.
Running alongside the Ciutat Vella is one of the world's great strolling boulevards, "Las Ramblas," crammed with buskers, newsstands, kiosks selling birds and other pets, and thousands of locals and foreigners who invariably provide superb people-watching. At the bottom of Las Ramblas, turn left at the monument to Columbus and follow the waterfront to Barceloneta, a gentrified waterfront neighborhood with great seafood restaurants, and onward to the Port Olimpic, known for its modern architecture, beach, and entertainment options popular with locals.
It is, of course, impossible to experience the essence of Barcelona without visiting some of its masterworks of early 20th-century Modernisme (Art Nouveau to the rest of us), most notably the icons designed by Antoni Gaudi. Many of these are in the 19th-century district called the Eixample. First and foremost, of course — by now practically a symbol of the city itself — is the Sagrada Familia church with its melted-wax spires. Other key stops on the Gaudi circuit include the Casa Batllo and La Pedrera, two buildings on the majestic Passeig de Gracia boulevard whose undulating lines are unsurpassed in any architecture I have ever seen. These sinuous lines also are apparent throughout an entire park, the Parc Guell, in the upper part of the city.
Finally, if you're traveling with children especially, you will appreciate Montjuic, a low, broad hill that is the site of an old fortress, the 1929 World's Fair grounds, several museums and various 1992 Olympic venues; trade fairs are still held here today. The World's Fair in particular left attractions such as a delightful colored fountain; the Palau Nacional (National Palace), which today houses the absorbing National Art Museum of Catalonia; and the Poble Espanyol, a theme park of architecture from all over Spain which today houses restaurants, shops, arts and crafts venues, and nightspots. One last noteworthy stop up here is the Fundacio Miro, a museum housing the whimsical works of Catalan artist Joan Miro.