Sagrada Família audio guide,
five stops, free.

Turn your back on the trees and look across the water. From this side of the pond you get the whole Nativity façade, four bell towers and three doorways, and this is the front Gaudí worked on to the end of his life.

Work started on this side in 1891, and he chose to begin here deliberately. If he had started with the Passion front on the far side of the block, which he wanted harsh and bare, as if made of bones, he thought people would take one look and walk away. So he put the joyful one first, facing east into the sunrise, and let it sell the rest of the project.

One of those four towers is Saint Barnabas, finished in 1925. It is the only tower Gaudí ever saw completed. He died the following June. The other three, dedicated to the apostles Simon, Jude Thaddeus and Matthias, went up in 1930.

Now the doors. Hope on the left, Charity in the middle, Faith on the right, with the names Joseph, Jesus and Mary cut into the columns in between. Each of those two columns stands on a turtle, one from the sea and one from the land, both of them symbols of time as something fixed; the chameleons at either end of the façade mean the opposite.

Above the central door there is a cypress tree in stone, the tree of life, and if you follow its branches you will find white doves roosting all over it. They stand for the men and women saved by redemption.

Here is the surprise. None of this was supposed to be the colour it is. Gaudí meant the whole façade to be painted, every arch band in a wide array of colours, every statue and every figure, so that the human beings would look as alive as the plants and animals crawling over them. It never happened. You are looking at a literally unfinished picture.

The way the figures were made is stranger still. To get them lifelike, the workshop moulded them from real people and real animals. Gaudí would then have the plaster version hoisted up onto the façade to see how it read from down here, and only if he was happy with it was the final version cut in stone.

At the far end of this wall, tucked into the base of one tower, is the door to the portal of the Rosary. Gaudí left it finished in 1897 as a worked example, a piece of the inside done properly so that whoever came after him would know what he had meant. It is the only interior in the whole basilica he completed himself.

You are inside now, standing in the transept: the Nativity doors are behind you and the Passion doors are directly across. The long axis of the church crosses here, the nave running away to your left towards the unfinished Glory front, the apse rising to your right. Stop walking and look up.

Gaudí told his assistant Joan Bergós what he was after, and Bergós wrote it down: intimacy with the spaciousness of the forest, this will be the inside of the temple. That is the whole brief for this space. The shafts are trunks. The swelling at the top of each one, where a classical building would put a capital, is a knot. Above it the column branches, at more than one height, and the branches hold up the vault, which is the foliage.

The columns are his own invention. Each one begins as a star and ends as a circle: a star-shaped base twisting clockwise and anticlockwise at once, doubling its points every time it climbs half the height and turns half the rotation, until the polygon is so nearly a circle that he hid the last of it inside an egg-shaped knot, to keep the stonecutting possible. He took the idea of the rising twist from a eucalyptus tree growing outside his workshop next door.

Here is something you can check yourself. Go to the nearest column, count the points of the star at its foot, and double the number. That is its height in metres. Six points, twelve metres. Ten points, twenty.

The count is also a ranking: it tells you what that column carries, and each rank got its own stone. The four with twelve points, at the corners of the crossing in the middle of the building, are dark red granite porphyry, the strongest stone here, because they hold up the central tower. Ten points is black basalt, eight grey granite, six a yellowish sandstone for the lightest load.

And none of them is doing the work the way it looks. The stone is a skin. Solid columns thick enough to carry this roof would have closed the floor in, so Gaudí thought about iron for the four main ones, painted gold, and settled in the end on reinforced concrete inside the cladding, as his right-hand man Domènec Sugranyes explained to a meeting of Catalan architects in 1923.

Every height in here is a multiple of seven and a half metres, and they rise as you go inward: the side aisles thirty, the central nave forty-five, the crossing sixty, the apse seventy-five. That ladder is deliberate. Gaudí wanted somebody coming in at the main Glory door, away at the far end of the nave on your left, to see the nave vault, then the crossing vault, then the apse vault, each one appearing over the top of the last.

The daylight falling on you comes through openings he designed, two hundred and eighty-nine of them, punched between the columns to lighten the roof. The vaulting over your head was closed only in 2000 and the roof went on in 2010, the year an unfinished building could finally be used as a church. Pope Benedict the Sixteenth consecrated it that November in front of six thousand five hundred people, with another fifty thousand following from the streets outside.

Out through the doors, across into the square, then turn round and look back up. From directly underneath you get what Gaudí was actually after here, and it has little to do with the sculpture.

He designed this front in 1911, when he believed he was dying. He had fallen ill, gone up to Puigcerdà in the Pyrenees, drawn up his will, and spent the time reading Saint John of the Cross. What came back down the mountain was a set of small sketches; his drawing of this porch was printed in the temple's own magazine in 1917.

His instruction was one sentence: this façade should be harsh and cruel, as if made of bones. Isidre Puig i Boada took down the longer version. Some may find it too extravagant, Gaudí said, but I wanted it to inspire fear; I am willing to sacrifice the building itself, to break arches, cut down columns, to give people an idea of how bloody the sacrifice is.

So look at what is holding the porch up. Six columns, and not one of them upright. They lean, and they are cut to look like strained tendons rather than supports: a structurally honest thing dressed up as a horrible one. Above them the pediment rests on eighteen more, every one of them a bone.

None of this existed in his lifetime. The foundation went in in 1954, twenty-eight years after he died, and the four bell towers, dedicated to the apostles James, Thomas, Philip and Bartholomew, were finished in 1976. In 1986 the sculptor Josep Maria Subirachs was given the sculpture groups. He spent a year with Gaudí's drawings before he cut anything, then moved into a small bedroom at the basilica and worked on nothing else, exactly as Gaudí had at the end. The cross went up onto the pediment in July 2018.

Now the thing above all of it. That is the tower of Jesus Christ, and on the twentieth of February 2026 the upper arm of its cross was lifted into place, finishing the outside of it. It stands 172.5 metres, and that figure is a ceiling rather than an ambition: Gaudí fixed it one metre below the summit of Montjuïc, because nothing he made should rise higher than something God made. It also makes this the tallest church in the world, eleven metres above the spire at Ulm.

Fourteen of the eighteen planned spires are standing. Four to go, on a church that has never taken a coin of government or diocesan money: the bookseller's donations paid for the start, and the people who come to look at it pay for the rest.