The building of Barcelona's Sagrada Familia

More than 140 years after the first cornerstone of Barcelona's Sagrada Familia basilica was laid, the "famously incomplete" church is inching towards completion with five of its six central towers now finished.

But "would-be" pilgrims to the iconic site "should not expect to see Antoni Gaudí’s structurally audacious masterpiece fully realised" until at least 2026, said The New York Times.

The Junta Constructora del Temple Expiatori de la Sagrada Família, a foundation that oversees the church's construction, said work had now been completed on two of the church's main towers. These towers join the two completed last year, collectively symbolising the four Evangelists – Matthew, Mark, Luke, and John – traditionally recognised as the authors of the canonical Gospels detailing Jesus's life.

This week saw the installation of the final sculptural piece on the tower of Matthew the Evangelist, followed by the crowning of the tower of John the Evangelist with the figure of an eagle.

The foundation said it hopes that the tallest planned central tower, which will represent Jesus, will be finished for the centennial of Gaudí's death in 2026.

Antoni Gaudí, "the brilliant and idiosyncratic Catalan architect", devoted much of the latter half of his life to designing and constructing the church. The cornerstone was laid in 1882, and Gaudí "worked intensively on the project until he died after being struck by a tram at the age of 73", said The New York Times.

The cathedral's construction, like that of most cathedrals, has been extremely slow, and faced disruption in the late 1930s due to the Spanish Civil War, during which "most of the designs and models" of Gaudí's cathedral were destroyed, said CNN. The current designs being used to complete his masterpiece are "based on surviving and reconstructed materials, as well as reimagined adaptations of the original".

Designated a Unesco World Heritage site in 1984, the Sagrada Familia was consecrated for religious worship by Pope Benedict XVI in 2010. Upon completion, it will claim the title of "the world's tallest church", surpassing Germany's Ulm Minster.