The Basílica i Temple Expiatori de la Sagrada Família (Basilica and Expiatory Church of the Holy Family) is a large Roman Catholic church designed by Catalan architect Antoni Gaudí (1852–1926). When Gaudí died in 1926, the basilica was only between 15 and 25 percent complete. The central nave vaulting was completed in 2000 and the main tasks since then have been the construction of the transept vaults and apse. The style of la Sagrada Família is variously likened to Spanish Late Gothic, Catalan Modernism and to Art Nouveau or Catalan Noucentisme. Together with six other Gaudí buildings in Barcelona, part of la Sagrada Família is a UNESCO World Heritage Site, as testifying "to Gaudí’s exceptional creative contribution to the development of architecture and building technology", "having represented el Modernisme of Catalonia" and "anticipated and influenced many of the forms and techniques that were relevant to the development of modern construction in the 20th century". The site is served by subway Line 2 and Line 5 at Sagrada Familia Station.

Casa Milà, popularly known as La Pedrera or "open quarry", a reference to its unconventional rough-hewn appearance, is a modernist building and a a World Heritage Site. It was the last private residence designed by architect Antoni Gaudí and was built between 1906 and 1910. Gaudí designed the house as a constant curve, both outside and inside, incorporating ruled geometry and naturalistic elements. One of the most notable elements of the building is the roof, crowned with skylights, staircase exits, fans, and chimneys. All of these elements, constructed out of brick covered with lime, broken marble, or glass have a specific architectural function but are also real sculptures integrated into the building. The building's unconventional style made it the subject of much criticism.

Casa Batlló is a renowned building located in the center of the city and is one of Antoni Gaudí’s masterpieces. The building that is now Casa Batlló was built in 1877; it was bought by the Batlló family in 1900 and they hired Gaudí to design the family home. Like everything Gaudí designed, it is only identifiable as Modernisme or Art Nouveau in the broadest sense. The ground floor, in particular, has unusual tracery, irregular oval windows and flowing sculpted stone work. The roof terrace is one of the most popular features of the entire house due to its famous dragon back design. Gaudí represents an animal’s spine by using tiles of different colors on one side. Due to the building's location and the beauty of the facilities being rented, the rooms of Casa Batlló were in very high demand and hosted many important events for the city.

Plaça de Catalunya (Catalonia Square; sometimes referred to as Plaza de Cataluña, its Spanish name) is a large square in central Barcelona that is generally considered to be both its city centre and the place where the old city and the 19th century-built Eixample (a chic extension of the city) meet. Plaça Catalunya was conceived in 1859, after the medieval city walls were demolished and ambitious designs for the city's public spaces were conceived under the guidance of notable urban planners. The plaza occupies an area of about 50,000 square metres. It is especially known for its fountains and interesting statues that are representative of Noucentisme, Neo-Classicism and different avant-garde movements.

The Palau de la Música Catalana (Palace of Catalan Music) is a concert hall designed in the Catalan modernista style. It was built between 1905 and 1908 for the Orfeó Català, a choral society founded in 1891 that was a leading force in the Catalan cultural movement that came to be known as the Renaixença (Catalan Rebirth). It was inaugurated in 1908. The rich decoration of the façade of the Palau, which incorporates elements from many sources, including traditional Spanish and Arabic architecture, is successfully married with the building's structure. Today, more than half a million people a year attend musical performances in the Palau that range from symphonic and chamber music to jazz and Cançó (Catalan song). Many of the world's best soloists and singers have visited the venue. It is a UNESCO World Heritage Site.

The Arc de Triomf (Arco de Triunfo) is a triumphal arch built as the main access gate for the 1888 Barcelona World Fair. The arch is built in reddish brickwork in the Neo-Mudéjar style. The front frieze contains the stone sculpture Barcelona rep les nacions (Catalan for "Barcelona welcomes the nations"). The opposite frieze contains a stone carving entitled Recompensa ("Recompense"), representing the granting of awards to the participants in the World Exposition. It can be accessed by the Regional Train at at Arc de Triomf Station or subway L1 at Marina Station.

Opened in 1963, the Picasso Museum houses one of the most extensive collections of artworks by the renowned 20th-century Spanish artist Pablo Picasso with 4,251 works exhibited by the painter. It is the first museum dedicated to Picasso's work and the only one created during the artist's life. The museum is housed in five adjoining medieval palaces, dating from the 13th century and 14th century. The buildings follow the style of Gothic civil Catalan. The permanent collection is organized into three sections: painting and drawing, engraving, and ceramics. These cover principally the early years of Picasso’s artistic life, such as his Blue Period from 1901 to 1904, but Picasso, his family, and his friends would bequest or loan other later pieces as well.

Santa Maria del Mar (Saint Mary of the Sea) is an imposing church built between 1329 and 1383 at the height of Catalonia's maritime and mercantile preeminence. It is an outstanding example of Catalan Gothic, with a purity and unity of style that is very unusual in large medieval buildings. From the outside, Santa Maria gives an impression of massive severity that belies the interior. In contrast with the exterior, the interior gives an impression of light and spaciousness. Some interesting stained-glass windows have survived from various periods. The spacing of the columns is the widest of any Gothic church in Europe—about forty-three feet apart, center to center.

Inaugurated in 1943, the Barcelona City History Museum (MUHBA) is a city museum that conserves, researches, communicates and exhibits the historical heritage of the city of Barcelona, from its origins in Roman times until the present day. t is responsible for a number of historic sites around the city, most of them archaeological sites displaying remains of the ancient Roman city, called Barcino in Latin. Some others date to medieval times, including the Jewish quarter and the medieval royal palace called the Palau Reial Major. The rest are contemporary, among them old industrial buildings and sites related to Antoni Gaudí and the Spanish Civil War.

The Barcelona Cathedral (full name: Cathedral of the Holy Cross and Saint Eulalia), is the Gothic cathedral and seat of the Archbishop of Barcelona. The cathedral was constructed from the 13th to 15th centuries, with the principal work done in the 14th century. In the late 19th century, the neo-Gothic façade was constructed over the nondescript exterior that was common to Catalan churches. The roof is notable for its gargoyles, featuring a wide range of animals, both domestic and mythical. The cathedral is dedicated to Eulalia of Barcelona, co-patron saint of Barcelona, a young virgin who, according to Catholic tradition, suffered martyrdom during Roman times in the city.

La Rambla is a street in the centre of the city that stretches for 1.2 kilometres, popular with tourists and locals alike. The course of La Rambla was originally a sewage-filled stream-bed. In the year 1377, construction started on an extension of the city walls to include La Rambla and El Raval. In 1440, the stream was diverted to run outside the new walls, and La Rambla gradually started turning into a street. Over the next few centuries, La Rambla became established as a centre of Barcelona city life, a long wide thoroughfare used for festivals, markets, and sports. Several large religious establishments were also built along the street during this period. Its origins as a watercourse are reflected in the paving design, which appears to ripple like water. Today, the tree-lined central promenade is crowded during the day and until late in the night. Along the promenade's length are kiosks that sell newspapers, souvenirs, and flowers; there are also street traders, performers, and pavement cafes and bars.

The Mercat de Sant Josep de la Boqueria, often simply referred to as La Boqueria, is a large public market with an entrance from La Rambla, and one of the city's foremost tourist landmarks. The first mention of the Boqueria market in Barcelona dates from 1217, when tables were installed near the old city gate to sell meat. It was not until 1826 that the market was legally recognized and construction began in 1840. The market officially opened in the same year. The inauguration of the structure finally took place in 1853. A new fish market opened in 1911. Today the market has a very diverse selection of goods.

The Gothic Quarter (Barrio Gótico) is the center of the old city. It was built primarily in the late 19th and early 20th century, though several buildings date from medieval times. The Barri Gòtic retains a labyrinthine street plan, with many small streets opening out into squares. It is served by subway L4 Jaume I Station.

The Gran Teatre del Liceu is an opera house opened in 1847. With 2,292 seats it is one of the biggest opera houses in Europe. It is a typical Italian horseshoe-shaped theatre. The history of Liceu premieres is a good instance of the evolution of European opera tastes. From the 1950s to now, the repertory has largely comprised the most performed titles in the world, including practically all the great 20th-century composers such as Bartók, Honegger, Gershwin, Berg and so on. Ballet seasons are also an important part of the theatre's activities with some of the best known companies in the world performing,

The Palau Güell is a mansion designed by the architect Antoni Gaudí for the industrial tycoon Eusebi Güell and built between 1886 and 1888. It is part of the UNESCO World Heritage Site ""Works of Antoni Gaudí"". The ornate modernist mansion is a historically significant example of early Gaudí architecture. The home is centered around the main room for entertaining high society guests. Guests entered the home in horse-drawn carriages through the front iron gates, which featured a parabolic arch and intricate patterns of forged ironwork resembling seaweed and in some parts a horsewhip. The main party room has a high ceiling with small holes near the top where lanterns were hung at night from the outside to give the appearance of a starlit sky.

Montjuïc Castle (Castell de Montjuïc) is an old military fortress, with roots dating back from 1640, built on top of Montjuïc hill. The foundation stone for the basic fortification was laid out in 1640. A year later, in January 1641, the fort saw its first battle, during the Catalan Revolt when the Principality of Catalonia challenged Spain's authority. Fifty years later, in 1694, new bastions and battlements were erected and the fortress became a castle. In the last 350 years Montjuïc Castle has played a decisive role in the history of Barcelona becoming a symbol of submission after the Catalan defeat to Spain in 1714. The castle is infamous in Catalan history books because of its role in the civil war from 1936 to 1939 when both sides of the conflict imprisoned, tortured and shot political prisoners at Montjuïc. Later in the 20th century, the castle became a military museum. It currently serves as a Barcelona municipal facility. The castle can be accessed by the Montjuïc cable car, a gondola lift that has its upper station near the castle entrance and connects, via the Montjuïc funicular, with the subway at Paral·lel Station.

The National Art Museum of Catalonia is the national museum of Catalan visual art situated on Montjuïc hill. It is especially notable for its outstanding collection of romanesque church paintings, and for Catalan art and design from the late 19th and early 20th centuries, including modernisme and noucentisme. The Museum is housed in the Palau Nacional, a huge, Italian-style building dating to 1929. It is one of the largest museums in Spain. The Museu Nacional Romanesque Collection is unmatched by that of any other museum in the world. Many of the works here originally adorned rural churches in the Pyrenees and other sites in Old Catalonia. The Gothic collection features a considerable number of Catalan works representative of Gothic art produced in the three large peninsular territories that formed part of the kingdom of Aragon – Catalonia, Aragon itself, and Valencia. The Palau Nacional is a huge building which embodies the academic classical style that predominated in constructions for all the universal exhibitions of the period. Its façade is crowned by a great dome inspired by St. Peter's Basilica in the Vatican City in Rome.

Camp Nou ("new field"), often incorrectly referred to as the "Nou Camp" in English), is the home stadium of FC Barcelona since its completion in 1957. With a seating capacity of 99,354, it is the largest stadium in Europe and the second largest association football stadium in the world in terms of capacity. It has hosted two European Cup/Champions League finals in 1989 and 1999, five matches including the opening game of the 1982 FIFA World Cup and the football competition final at the 1992 Summer Olympics. The facilities now include a memorabilia shop, mini-pitches for training matches, and a chapel for the players. The stadium also houses the second-most visited museum in Catalonia, FC Barcelona Museum, which receives more than 1.2 million visitors per year.