This is going to be a very full day, so make an early start at the Plaça de Catalunya. Spend the morning wandering down La Rambla to the Mirador de Colón beside the port. Return via the Plaça Reial and explore the neighboring Barri Gòtic with its central Catedral. Then walk across to the Raval and Poble Sec districts on the western side of La Rambla. From there, take the funicular to the top of Montjuïc for a fine view of Barcelona and its harbor. Explore the gardens and castle museum and, if there's time, pop into the Museu Nacional d'Art de Catalunya for a glimpse of the finest collection of Romanesque relics in Spain. In the evening travel by Metro to visit Antoni Gaudí's unfinished masterpiece, La Sagrada Família, and the Parc Güell.

1. Plaça de Catalunya

Located at the top end of La Rambla and midway between the medieval Old City and the 19th-century Eixample, this circular plaça, with its fountains and sculptures, is the cultural hub of Barcelona. Surrounded by large stores, open-air cafes, and hotels, it's a place to watch passersby, listen to the Latino buskers, feed the pigeons, and even try to join in and dance the sardana on festive occasions. As the afternoon proceeds it gets increasingly crowded and colorful.

2. La Rambla

Also known as Las Ramblas, this mile-long avenue is divided into five distinct sections named, successively, Canaletes, Estudis, Sant Josep, Caputxins, and Santa Mónica. It's a stage-set of human statues, jugglers, singers, eccentrics, caged small animals, kiosks, cafes, and vibrant flower stalls, all shaded by a leafy canopy of huge plane trees. Originally called ramla (riverbed) by the Arabs, it's the favorite evening stroll for Barcelonans and visitors alike. For year-round atmosphere, there's nowhere else like it in Spain.

3. Mirador de Colón

Situated at the port end of La Rambla, this ornate bronze statue in honor of the Genovese sailor who discovered you-know-where was built during Barcelona's 19th-century industrial boom. After 10am you can get to the top by elevator and enjoy marvelous views of the harbor and Ciutat Vella. Spot the deliberate mistake: Columbus is pointing east across the Mediterranean to Mallorca instead of west toward the Atlantic.

4. Take a Break — Café de l'Opera

Halfway down La Rambla, Café de l'Opera is a 19th-century Parisian-style cafe. Its murals, iron columns, and wall mirrors with etchings evoke a more elegant age, but the waiters with bow ties will serve you with  indifference. So don't eat, but enjoy the place for its atmosphere, quality coffee and the view of the non-stop activity outside.

5. Plaça Reial

This is one of the city's great old squares, with neoclassical pillars and archways, 19th-century lampposts, slender ageing palm trees, and enough semi-resident marginals to do justice to any Almodóvar movie worth its salt. More ominous in the past, today it is virtually a tourist attraction. Watch out for pickpockets, though.

6. Barri Gòtic

Said to be the largest inhabited (and probably most densely populated) medieval quarter in Europe, the narrow-alleyed Barri Gòtic really needs a minimum of a half a day's leisurely exploration, so if you're in town for more than 3 days, come back again (and again) to do it full justice. At night its illuminated streets and buildings give it a magical touch. If you're only here a day, then the Catedral is an absolute must. Also not to be missed are the central Plaça del Rei, with its two key monuments, and the Museu d'Historia de la Ciutat, built over a complete subterranean Roman township. Another must-see is the Palau del Rei, where Columbus introduced American Indians to Spain's monarchs for the first time in its Salódel Tinell.

7. Catedral 

Originally built on the site of the old Roman town, this monumental place of worship was begun in the 13th century and finished in the 15th. (No hurry in those days!) It has seen many changes over the centuries, although it was mercifully one of the few buildings to be spared the destructive fury of the Civil War. Here the young Santa Eulàlia—cruelly martyred for protesting her Christianity during Dacian's repressive rule—is buried. Don't miss the 14th-century choir stalls, chapter house, and roof, or the delightful cloister, which bucolically hides tall palms, a cluster of orange trees, and a pond with geese amid the surrounding Gothic and Renaissance splendor.

8. Take a Break — Can Culleretes

For an atmospheric lunch, you can't beat Barcelona's oldest restaurant (established in 1786), Can Culleretes. It's tucked away in a secretive lane in the heart of the Barri Gòtic. You won't be the only non-Catalan visitor—the place is in too many guidebooks—but the restaurant is a monument, the service and decor from another age, and the traditional food and wine pretty good.

9. Montjuïc

Topped by an imposing castle, which is now a military museum, this distinctive hill on the city's west flank offers some of the best vistas of the Catalan capital. After the radical improvements prior to the 1992 Olympics (don't forget to take an outside peep at the stadium), it's now also the city's greatest green zone, with a wealth of walkways, parklands, leisure areas, and cultural attractions to explore. Get there by the funicular from Poble Sec or by the more vertiginous Telefèric de Montjuïc, which carries you high above the harbor.

10. Take a Break — Montjuïc Castle Café

This unpretentious self-service cafe, tucked away inside the castle with a patio section where you can sit outside in good weather, is a great spot for relaxing and savoring the old "castell" ambience.

11. Sagrada Família

In the evening, cross the city by Metro Line 5 to the Sagrada Família, abandoned for decades and still unfinished. The cathedral finally saw restoration and expansion work carried out when its hermit-like architect, Antoni Gaudí (who was killed by a tram in 1926 and whose tomb can be viewed in the crypt), came back into fashion in the 1990s. The four original spires—by the master himself—are generally acknowledged to be far superior to the additional quartet designed by modern architects. Take a ride up to the top of one of the towers and enjoy the fine view. Loved and reviled in equal measure, the building remains unique. Current construction progress is slow, however, and even the most optimistic forecaster doesn't see the whole thing reaching completion for at least another decade.

12. Parc Güell

Take Metro Line 5 to Diagonal and Line 3 to Lesseps, and walk up to Parc Güell in time for sunset. You can imagine gremlins living in this unique fairy-tale park located high up in the city and loved by children and adults alike. Look out for its mosaic serpent and Hansel-and-Gretel houses at the entrance (one of which is a tiny museum, the Centre d'Interpretaciói Acollida, devoted to describing creator Gaudí's building methods). At its center, up some steps, the Banc de Trencadís—a multi-colored ceramic bench—curves around a spacious esplanade, while behind it footpaths climb into the pine woods of Vallcarca and Monte Carmel, offering scenic views through the trees of the city below.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.