Las Ramblas: It would be hard to miss Las Ramblas, as the city's main thoroughfare is virtually opposite the cruise terminals. The fabulous promenade -- almost a mile long -- leads from the port to Placa de Catalunya, the center of old Barcelona. It's lined with shops, cafes, flower stalls, street performers and a wonderful food market called Mercat de Sant Josep de la Boqueria (just Boqueria, for short). You'll pass by the Gran Teatre del Liceu, Barcelona's circa-1848 opera house. Las Ramblas ends at the Placa de Catalunya, a huge plaza that's the heart of the city and is surrounded by shops and cafes. This is a great place to stroll, but watch your belongings -- it's a bit of a tourist trap so there may be pickpockets.
Basicila de la Sagrada Familia: Barcelona's funkiest church, Basicila de la Sagrada Familia was designed by Gaudi and has become a symbol of the city. The most unusual thing about it? It's not finished yet! He began working on it in 1883 and designed intriguing features such as the bell towers, covered in Venetian mosaics, and the nativity-themed facade, with doorways representing faith, hope and charity. Gaudi devoted the last 16 years of his life to working on the extraordinary church, and services are held in the crypt where he is buried. A great way to experience Sagrada Familia is to take the elevator (when available) to the top of one of the towers; there's an awesome view from that height. (Admission requires a separate ticket, booked in advance.) We found the additional-fee audio tour a bit confusing -- we often had to search for the 'stations' and while context helped in the understanding of the basilica, many times we were instructed to "sit and meditate." A guided tour is the way to go if you're really into learning about Gaudi's pivotal work, as it gives you the ability to ask questions. Also, save some time to spend in the church museum. (Calle Mallorca 401; open daily from 9 a.m. to 6 p.m. November to February 9; 9 a.m. to 7 p.m. March and October; 9 a.m. to 8 p.m. April through September and 9 a.m. to 2 p.m. December 25, 26 and January 1)
Architect Antoni Gaudi also designed Palau Guell, a gorgeous late 19th-century palace. Once the home of a wealthy count, it was built with underground stabling for the horses and carriages of visitors. (Nou de la Rambla 3-5; open weekdays from 10 a.m. to 5:30 p.m., closed on Mondays)
Casa Batllo: Perhaps Gaudi's best-known home design is that of Casa Batllo, located on Passeig de Gracia in the heart of Barcelona. Inspired by the rolling waves of the ocean as well as dragons, the house is hard to miss, even on a street heavy with ornate architectural styles. A neat video-guide with augmented reality accompanies your audio tour, allowing you to see what the spaces would have looked like in days past. (Open Monday to Sunday from 9 a.m. to 9 p.m., last entry at 8 p.m.; Passeig de Gracia, 43, 08007 Barcelona)
La Pedrera: For more Gaudi architecture (without La Sagrada Familia's crowds), consider a visit to Casa Mila, more popularly known as La Pedrera. The building, which was used as a family dwelling in the early 20th century, is quite stunning, and the living quarters lend incomparable insight into the local lifestyle during that era. The architecturally and visually shocking rooftop chimneys that you can actually walk through and around are truly a sight to be seen (and touched) -- and the view of the city is breathtaking. (Passeig de Gracia 92; open most days from 9 a.m. to 8 p.m. and 9 p.m. to 11 p.m.)
Park Guell: Another Gaudi design, Park Guell is a pleasant public park overlooking the city -- a maze of tropical flowers and colorful accents. The land was bought by a rich count in 1900 and earmarked as a miniature garden city for the wealthy. Gaudi set to work creating a park and homes, but the houses were deemed too fanciful for the day and the project was abandoned in 1914, becoming another testament to the architect's inimitable creativity. The entrance is guarded by a mosaic lizard and two gatehouses; one of the latter houses a souvenir shop. Here, you'll also find performers and craftsmen selling handmade souvenirs at bargain prices (yes, haggling is permitted). Watch for hordes wielding selfie sticks -- this is one of the most popular vistas in all of Barcelona.
Barcelona Neighborhoods: In Barcelona's Gothic Quarter, or Barri Gotic, architecture dates to the 13th century, so this area has a wonderfully "Olde Europe"-style atmosphere. Streets are winding and narrow, with numerous boutiques and antique and artisan galleries. El Born is a trendy neighborhood within the Barri Gothic area, known for its hip restaurants, cafes, galleries and shops. One of the area's best-known attractions is the Museu Picasso (Carrer Montcada, 15-23; open 10 a.m. to 5 p.m. Monday; 9 a.m. to 8:30 p.m. Tuesday to Sunday; until 9:30 p.m. Thursdays). Founded in 1963, it is Barcelona's most visited museum and can be found in a series of beautiful medieval stone mansions in an atmospheric narrow street. Although Pablo Picasso was born in Malaga, he spent much of his life in Barcelona, and the museum contains a collection of more than 3,000 of his paintings and sketches created from 1890 through to the 1950s. Parts of Barcelona Cathedral (Placa de la Seu; open daily from 8 a.m. to 7:30 p.m.) date to 1298, but it wasn't actually completed until the late 19th century. It's a dramatic example of Gothic style with gargoyles along the outside facade. Santa Maria del Mar (Carrer Montcada at Placa de Santa Maria; open weekdays from 9 a.m. to 8:30 p.m., and from 10 a.m. on Sundays) is known as the "people's church," and only took 50 years to build in comparison. Its structure is quite elegant and unusually simple, partially due to damage during the civil war.
Barcelona Stadiums: Sports enthusiasts will enjoy a trip to Olympic Stadium (the double-decker hop-on, hop-off tourist buses head here). The stadium existed before the Olympics but it was completely remodeled in 1992 for the occasion. These days, the stadium is used for various events. Similarly, soccer fans can visit the Camp Nou Stadium, home of FC Barcelona, or Barca as the team is known locally. Open daily, the stadium tour takes visitors through the museum and culminates with a visit to the changing rooms and the tunnel, leading to a panoramic view of the vast stadium. Three miles west of the city center, the stadium is close to the Collblanc or Badal metro stops.
Barceloneta: This one-time fishing village is now a beachfront neighborhood filled with narrow, brightly colored houses, and has a pretty nice beach facing the Mediterranean. Following the waterfront, continue on to Port Olimpic, which has shops, cafes and bars. Port Vell, just beyond, has restaurants and Maremagnum, a big fancy shopping mall complete with IMAX theater. Gambling aficionados should check out the Casino de Barcelona (Calle de la Marina; open 24 hours.); beyond slots and tables, there's also a floor show and disco.
Montjuic: The village of Montjuic rises 700 feet above the city's commercial port and is chock-full of cafes, boutiques, art galleries and museums. Not to be missed is Museu Arqueologic (Passeig Santa Madrona 39; open daily), which showcases artifacts from prehistoric cultures in both Catalonia and the Balearic Islands. Another highlight is the Fundacio Joan Miro (Parc de Montjuic; open 10 a.m. to 8 p.m. Tuesday, Wednesday and Fridays April to October, 10 a.m. to 6 p.m. on those same dates November to March; 10 a.m. to 9 p.m. Thursdays; 10 a.m. to 8 p.m. Saturdays and 10 a.m. to 3 p.m. Sundays), which features tapestries, paintings and sculptures of Catalonian artist Joan Miro. Another key art museum is the Museu Nacional d'Art de Catalunya (Palau Nacional, Parc de Montjuic; open Tuesday to Saturday from 10 a.m. to 8 p.m. in summer, 10 p.m. to 6 p.m. in winter, and Sundays from 10 a.m. to 3 p.m year-round.); it's got one of the world's premier collections of Romanesque art.
Church of Colonia Guell: While Gaudi's unfinished masterpiece Sagrada Familia is always busy, you can avoid the crowds by heading to another of his projects, also never completed. In 1898, Gaudi was commissioned to build the church of Colonia Guell by his good friend Eusebi Guell, a prominent local businessman. Guell wanted the church for the workers' village that he had constructed around his textile factory. Testing architectural techniques later used in the Basilica de la Sagrada Familia, Gaudi started work in 1908, but when Guell died in 1914, just as the crypt was finished, building work was stopped because of lack of funding. The church (also referred to as the Gaudi Crypt, although he is not buried there) is a 20-minute train ride out of the city. (Open Monday through Friday from 10 a.m. to 7 p.m. and Saturday and Sunday from 10 a.m. to 3 p.m.)
Temple of Augustus: Hidden in the Gothic Quarter on Carrer Paradis is one of Barcelona's biggest sightseeing surprises. Inside a small medieval courtyard are four imposing Corinthian columns that have survived the centuries and are all that remain of a Roman temple dedicated to emperor Caesar Augustus. It is located inside the Centre Excursionista de Catalunya. (Carrer del Paradis 10; open Mondays from 10 a.m. to 2 p.m., Tuesdays to Saturdays from 10 a.m. to 7 p.m. and Sundays from 10 a.m. to 8 p.m.)
Horta Labyrinth Park: Although it's Barcelona's oldest park, this green gem in the northern part of the city is off the main tourist trail. To preserve its peaceful beauty, only 750 people are admitted each day and entrance is a little more than 2 euros per person. Only groups can reserve entry; however, the entry limit is unlikely to cause any problems during the week because mostly locals visit the park. If the entry limit is reached, visitors are politely asked to not linger more than an hour to allow others inside. The 18th-century park offers a maze, pretty gardens, statues and water features. The easiest way to get there is to take the green line metro L3 to Mundet; the park is a five-minute walk from the subway. Entrance is free on Wednesdays and Sundays. (Passeig Castanyers, 1; ppen daily from 10 a.m.)
Refugi 307: The tunnel is one of more than 1,000 built to shelter citizens from the bombing raids during the Spanish civil war, and part of the Museu d'Historia de la Ciutat. Open to the public on Sundays (weekdays by appointment only), the tunnel, which includes an infirmary, brings this dark period of history to life. (Carrer Nou de la Rambla 169; open Sundays with guided tours in the morning and afternoon, Monday through Saturday to reserved groups only.)
Museu Moto: Barcelona has the highest number of motorbikes per capita in Spain, and this motorcycle museum celebrates the city's love affair with two wheels. The museum can be found in the rather incongruous setting of the former Saint Felip Neri Convent in the Gothic Quarter. It charts the history of the Catalan motorcycle from 1905 to the present day, and the pioneers behind the industry. While motorbike aficionados will recognize names such as Montesa, Bultaco and Ossa, the exhibits reflect the fact that the region was once home to 150 different manufacturers. (Calle Palla 10; open daily 10 a.m. to 6 p.m.)
Museu de l'Erotica: For something different, visit this unique museum on Las Ramblas. More than a tawdry peep show, the museum (the only of its kind in Spain) showcases sexuality through the ages and contains a variety of artifacts from all over the world -- everything from Buddhist sculptures to modern-day photography and art. The museum is open year-round. (Ramblas 96; open every day from 10 a.m. to midnight.)
Montserrat: "The Serrated Mountain" -- more than 4,000 feet high -- is an exquisite setting for a working monastery home to Benedictine monks. The original church opened in 1592, though Montserrat remains an ongoing work in progress. If you're visiting in the afternoon (around 1 p.m.), try to catch the male choir singing Virolai, the hymn of Montserrat (although this is not held every day so manage expectations). An afternoon mass is typically held, with a short prayer recited in a few different languages. While the complex includes shops and cafes, the real points of interest are the basilica with its Black Madonna -- the soul of the monastery -- and breathtaking hiking trails along the mountain (Sant Jeroni is a popular trek). Other features include the Placa de Santa Maria, with its Gothic cloisters, and the Museum of Montserrat, which exhibits works of art from Catalonia, West Asia and a healthy collection of works from other regions. It's easy to get there; take the Ferrocarriles Catalanes train that runs hourly from Barcelona's Placa Espanya (see below).