The Sagrada Familia involved Gaudi throughout his entire life, and in it he expressed his intellectual ideas as well as his religious beliefs, which became more and more mystical as he aged. At the same time, the Sagrada Familia represents the extreme result of an art nouveau interpretation of the Gothic style. Work began on the Sagrada Familia – still in large part unfinished today – in 1882 on a neo-Gothic design by the architect Del Villar; by 1893 only the area of the apse had been completed. Even so, and despite a sea of difficulties, not all of them financial, the project was in large part completed in 1906. ‘The straight line belongs to man, the curved line belongs to God: so affirmed Gaudi, who had become, around the end of the 19th century, the proclaimer of a new mystical-visionary architectural religion, arranged and supported by a geometry of parabolic curves, ellipses, hyperbolas. Gaudi’s design follows a complex symbolic programme, expressed with an exuberant and imaginative vocabulary that innovates the structure and its decoration, no longer separate but fused. With a narration that unites popular figures, learned citations, and religious symbols, Gaudi presents realistic and allusive iconography at the same time. The decoration sprouts organically from the architecture, modifying and modelling the geometric structure of the fronts and the towers and transforming the vertical supports into a forest of arboreal shapes. The extraordinary organization of the nave and vaults, conceived on the basis of light and acoustics, or the articulation of the astonishing facade, inspired by the theme of the Nativity – with its incredible spiralling towers – communicate both dynamism and stability, stupor and reverence, religious piety and love for nature, all of it pervaded by a vague sense of suffering. The work proceeded at such a slow pace – Gaudi saw incompleteness and imperfection as necessities – that when the architect died, in 1928, only the first of the four towers of the Nativity facade had been completed; in 1976, the Passion facade was completed. Gaudi has thus left a very special legacy to Barcelona, and in the style of the great medieval cathedrals, the construction of this temple has become an undertaking for the city itself, coming to involve generations of architects and patrons.