Barri Gotic & Ciutat Vella
Columbus was received by catholic kings at the Royal Palace when he returned from his first travel to America. Catalonia parliament meets at the Generalitat Palace. The Cathedral was built over a roman temple, it was begun in romanesque style, but was finished like gothic. It keeps the rests of the city martyr St. Eulalia.

Las Ramblas is an alive commercial pedestrians walk, beginning at Plaça de Catalunya and arriving to Monument to Columbus, which has become an universal symbol of the city. This statue stands over a 60 meters column and may be visited by lift.
Other interesting places here include the old roman walls of the city, the History museum and the Maritim museum.
 

Modernist art
The Eixample district is crowded with modernist buildings: The Casa Terrades (Casa de las Punxes), The Hospital de la Santa Creu y de Sant Pau and the museum Fundació Tapies.
If there's an universal artist from Barcelona, it's the modenist Gaudí. His works include: The Casa Batlló and the Casa Milá (La Pedrera). The Parc Güell is a very imaginative place not to be missed where Gaudí lived for 20 years, with colorful mosaics and the biggest bench in the world.

The still unfinished Sagrada Familia become the obsessive personal project of Gaudí. He imposed his personal charasteristic style on its neogothic style. The city can be viewed from the top of the bell towers, after going up by a 400-step stair!.
 

Other places
Over the top of Montjuïc mount can be visited the Palace, the Fundació Joan Miró and the Poble Espanyol, which resembles villages from different areas of Spain. Near is the Parc Joan Miró. The Parc de la ciutadella, includes sculptures, a lake and fountains from the universal exhibition celebrated in 1888.
Import places are also the Picasso Museum, the Olimpic City and the Contemporary Art museum.
 

More info at:
      . http://www.barcelona-on-line.es/eng/turisme/bcn.htm