Antoni Gaudi’s magnum opus, a project which he devoted himself to for 43 years until his death in 1926. The building, which is a combination of Gothic, Catalan Modernism, and Art Nouveau styles, combines all of the elements that Gaudí used and experimented with in his earlier works - the predominance of wavy curves over straight lines, parabolas instead of circles, the use of vegetal and other organic motifs, intricate decoration and detail, and brightly colored glass and mosaics. Since it is the second most visited site in Spain (the Alhambra in Grenada is the first), you really have to buy timed-entry tickets well in advance