Work in progress: Sagrada Familia

Construction of the Sagrada Familia started roughly 125 years ago Photograph: Getty

Gaudí spent 40 years overseeing work on the building but it was far from finished when he died in 1926 Photograph: Murdo Macleod

Jordi Bonet, aided by a sculptor and a team of 40 builders, went to work on finishing the edifice after Gaudí's death Photograph: Toni Albir/EPA

Josep Maria Subirachs worked on the building's west facade, which depicts the passion of Christ Photograph: Tibor Bognar/Corbis

Close-up of the door of the passion facade Photograph: Sutton-Hibbert/Rex Features

Gaudí refused to stick to a blueprint during construction, preferring to make changes as work progressed Photograph: PhotoDisc/Getty

Gaudí's original plans were also badly damaged by anarchists during the Spanish civil war Photograph: Barry J Holmes/Rex Features

Tourists look at the Sagrada Familia from the roof of Barcelona's La Pedrera building in 2002, the 150th anniversary of Gaudí's birth. Photograph: Santiago Lyon/AP

The building's design incorporates spirals, such as this bell-tower staircase Photograph: Kevin Foy/Rex Features

In 2005, the Sagrada Familia was joined on the Barcelona skyline by the Agbar (Aguas de Barcelona) tower, designed by French architect Jean Nouvel Photograph: Cesar Rangel/AFP

A group of Spanish artists and architects fear that the final version of the Sagrada Familia will bear little resemblance to Gaudí's vision Photograph: Grant Faint/Getty