Martin Filler at the New York Review of Books:
Although sacred structures of all sorts have been central to every culture throughout history, religious architecture has attained even greater importance in times of social upheaval. This was certainly true in mid-nineteenth-century Barcelona, the ancient Mediterranean port that became an economic powerhouse with the advent of industrialized textile manufacturing. As the strains caused by this rapid shift from small workshop to large factory production worsened, many felt that the Roman Catholic Church hierarchy was unresponsive to the travails of increasingly downtrodden urban laborers. Thus during the 1870s pious (and wealthy) barcelonés conceived a monumental building project for a working-class neighborhood that they hoped would stem religious disaffection by harking back to the devotional fervor, communal brotherhood, and civic pride fostered by the grand cathedral construction campaigns of the Middle Ages.
The result is one of the most celebrated shrines in Christendom, known in Catalan as the Temple Expiatori de la Sagrada Família (Expiatory Temple of the Holy Family). It was begun in 1882 using the conventional neo-Gothic designs of Francisco de Paula del Villar, who after two years of persistent quarrels with diocesan supervisors quit and handed the job over to his largely untested assistant Antoni Gaudí.