After raising the money to buy the land for the Temple Expiatori de la Sagrada Familia, Josep Maria Bocabella asked the city council to recommend an architect. They recommended Francesc de Villar, who started work along with consultant architect Joan Martorell, whose assistant was the young Antonio Gaudí. Bocabella thought that de Villar's estimated costs were rather high, and he asked Martorell what he thought. He thought they were rather high, too, and de Villar went off in a huff. Since it was Martorell's statements that led to de Villar leaving, he did not want to take over the job, and suggested that it be given to Gaudí.

Meanwhile, Bocabella had had a dream. He dreamt that the man who finished the church would have blue eyes. Martorell had brown eyes, Gaudí's were blue.

Gaudí completely redesigned the building, while making use of the foundations that had already been laid for the apse. One radical change was in the orientation of the church: every other church in Europe is built on an East-West axis, with the altar at the east and the main doors at the west. Thus the congregation when facing the altar is facing the rising sun and also facing Jerusalem. La Sagrada Familia is on a North-South axis, with the altar and apse at the north. The reason for this is to be found in the symbolism of the church's three façades: the façade of life, with imagery of plants and animals, the birth of Christ and his early life, faces the east, so the sun shines on it in the morning, in keeping with its theme of beginnings. The façade of death, with imagery of the passion, faces west, towards the setting sun, at the end of day. The southern, principal façade, lit by the glory of the midday sun, is to be the façade of the glory of Jesus. Its symbolism will address the life of men and what is to come after.

Bocabella's intention was to provide a church for the people paid for by the people. The construction work has therefore been financed entirely by voluntary donations. This explains its slow progress until recent years. At present, only technical constraints determine the speed of construction, which is expected to be finished in twenty to forty years, depending on the speed of relevant technical innovation. The difference was made by the 1992 Olympic Games in Barcelona, which led to a huge increase in the number of tourists visiting the church. It is now the most visited building in Spain, attracting more visitors even than the Alhambra or Escorial. And every visitor makes a voluntary donation in order to enter.

In Gaudí's lifetime the apse and much of the façade of life were finished. Only one of the façade's towers had been finished when he was run over by a tram in 1926; the rest were finished in 1929, while the decoration was completed in 1933. When I first visited the church in 1989 the future nave was hinted at by the first couple of metres of many of its pillars and work was proceeding slowly on the façade of death. As of last Thursday the façade of death was long finished, with stark sculptures by the prominent Catalan sculptor Josep Maria Subirachs, and over fifty workmen were working full time to finish the vault of the nave. When that has been done serious work can start on the main façade.

The highest tower, representing Christ, will be 170 metres tall. This is three metres lower than the summit of Montjuic, the highest point in Barcelona. Gaudí said it had to be lower than the mountain because man should not try to outdo God. It will still be a lot of stone. To carry the immense weight, the four pillars at the crossing (where the transepts cross the nave) are made of porphyry, the hardest rock after diamond.

The profiles of the towers and arches are catenary curves. They pass all their weight down to their own foundations, and the structure stands alone without buttresses. Gaudí was no lover of mathematics, and to avoid having to solve cubic equations to draw the curves he made upside-down string models, hanging bags of lead weights from the strings to represent the load the arches and vaults would later bear, and then copied the curves of the strings.