Notre-Dame de Paris audio guide,
five stops, free.

Stand back on the parvis far enough to take in the whole front: one flat, calm, nearly square face, sixty-nine metres to the tops of the towers. Le Corbusier called it a pure creation of the spirit, governed by the square and the circle. Find the circle first. It is the west rose, 9.6 metres across, dead centre, made around 1225.

Now look for the thing that is not symmetrical. The two towers look like twins and are not. The one on your left, the north tower, is slightly larger, and so is its buttress. The south tower went up first, from around 1220, and the north one between 1235 and 1250. Spires were considered for both in the thirteenth century and never built, which is why they stop flat.

The front was begun in 1200 under bishop Eudes de Sully, carried on under Guillaume d'Auvergne, confessor to Saint Louis, and finished in about fifty years by a succession of master builders whose names are lost.

Drop your eyes to the long row of crowned figures above the three doors, twenty metres up. That is the Gallery of Kings: twenty-eight of them, for the twenty-eight generations of the kings of Judah before Christ. During the Revolution they were taken for kings of France and destroyed or mutilated. Not one of them up there now is medieval. They were carved again in the nineteenth century by the workshops of Adolphe-Victor Geoffroy-Dechaume, and the restorers allowed themselves a joke. In 1860 the sculptor Chenillon left inscriptions on some of the new kings, naming the faces: the architect Eugène Viollet-le-Duc is up there with the features of King Ela, his colleague Lassus as Amaziah.

The real heads turned up in 1977, twenty-one of them, dug out during building work on the rue de la Chaussée-d'Antin in the ninth arrondissement. They are in the Musée de Cluny now, and they still carry traces of paint, which is the proof that parts of this front were once coloured.

Above the kings, the Virgin between two angels in front of the rose is Viollet-le-Duc's commission too, made by Geoffroy-Dechaume in 1854, and Viollet-le-Duc again set Adam on one side of the rose and Eve on the other.

Viollet-le-Duc is the name you will keep hearing today, and there is a reason. By the 1830s this building was in such a state that Paris officials considered pulling it down. Victor Hugo's novel of 1831 made the city look at it again, and in 1844 Lassus and Viollet-le-Duc were appointed to restore it. The pale colour came later still: from 1963 the culture minister André Malraux had the front cleaned of centuries of soot.

High in the south tower, on your right, hangs Emmanuel, the great bell, cast in 1683 and named by Louis XIV: thirteen tonnes, with a clapper of five hundred kilos, ringing in F sharp. It is the only bell here the Revolution did not melt down.

On the night of the fire in April 2019 the flames reached the north tower, where eight bells hung. The fear was that if the bells fell they would wreck the tower and endanger the other one, and the whole cathedral with it. A team of firefighters climbed the south tower, crossed over, and fought the fire underneath the bells. The front you are looking at is the one they saved.

Before you join the queue, look down. Somewhere in the paving of this square is a small marker, kilometre zero, the point from which the roads of France are measured out of Paris.

You are in the ambulatory now, the walkway that runs right round behind the choir, and the wall of carved and painted scenes at your shoulder is what is left of a fourteenth-century screen. Its job was silence: it gave the canons at prayer inside the choir a screen against everything happening out here.

If you came up the north side, you have passed the first half: the life of Christ from the Visitation to the Garden of Olives, fourteen scenes that run into one another without a break. It was carved under the architect Pierre de Chelles, who designed the choir's decoration and then, in 1316, left to work on Chartres.

This south side is different, and it is worth comparing. Jean Ravy took over as master of works, and for twenty-six years this was his. The subject is what happened after the Resurrection: Christ appearing to Mary Magdalene in the garden, dressed as a gardener, then to the holy women, to Peter, to the two disciples at Emmaus, to Thomas, to the apostles together. Nine scenes, each boxed off by its own small columns. The cathedral calls a cycle this complete rare in medieval sculpture. Look at the carving itself. The north wall is high relief, calm and clear. Here the figures stand fully in the round, the folds are stiffer, and every scene is crowded with detail.

Find Thomas. He kneels in a blue robe and puts his finger into the wound in Christ's side, and the other apostles watch from the windows of little towers on either side. The Latin underneath says it plainly: Christ appears to the ten apostles and to Thomas.

Ravy put himself into this wall, kneeling at its edge. He died in 1344 and his nephew Jean le Bouteiller finished the work in 1351. The man who paid for it, a canon called Pierre de Fayel, had himself carved kneeling at the end as well, and that figure is in the Louvre now.

What you see is only the sides. The screen once ran right round the choir; in the eighteenth century its east end was cut away for classical marble and its west end, a rood screen closing off the nave, came down.

The colour is not a modern idea. In the nineteenth-century restoration a restorer named Caudron set out to preserve the original paint rather than strip it off, and it has been renewed since, in the nineteenth and twentieth centuries. Before you walk on, look back along this wall once more: blue robes, red borders, a gold ground, restored paint on the medieval scheme, on stone carved nearly seven hundred years ago.

Cross the Pont au Double to the left bank and turn round. From here you get the long south side of the cathedral: the nave with its flying buttresses, the south transept front with its rose, and over the crossing, where the arms of the cross meet, the spire.

It is not the first spire here. The original went up between 1220 and 1230; five centuries of wind bent and weakened it, and it came down from 1786. Jean-Baptiste Lassus began a new one, and after his death in 1857 Viollet-le-Duc took it over, basing the design on the spire of Orléans Cathedral. The one he finished in August 1859 was ninety-six metres high, eighteen more than the original: an oak frame from Champagne, built by the carpenter Auguste Bellu, under about two hundred and fifty tonnes of lead.

Round its base he set sixteen copper statues by Geoffroy-Dechaume: the twelve apostles, three to each side, each group led by one of the four symbols of the evangelists, an ox, a lion, an eagle and an angel. The apostles all looked out over Paris except one. Saint Thomas, patron saint of architects, turned back to look up at the spire, and he had Viollet-le-Duc's face.

A restoration of the spire began on the eleventh of April 2019, and the sixteen figures were lifted off by crane for repair. Four days later the roof caught fire. The spire burned, and when it fell it brought down seven hundred and fifty tonnes of stone and lead and broke through part of the vaults. The cockerel from the top, which held a fragment of the Crown of Thorns that Viollet-le-Duc had put there himself, was thought lost. It was found in the rubble the next day, damaged but mostly whole.

The government announced a competition for a new design, and the ideas included a carbon-fibre spire covered in gold leaf. In July 2020 the decision went the other way: rebuild Viollet-le-Duc's spire exactly, to the same plans. A new cockerel went on top on the sixteenth of December 2023, carrying the same relics and the names of two thousand people who worked on the rebuilding, and when the six-hundred-tonne scaffold came down in February 2024, this was underneath.

So what you are looking at is new oak and new lead, and a design from 1859.

Before you go, look along the flank below it, where the flying buttresses leap over the side aisles in a single span. Further east, round the choir, Jean Ravy built fourteenth-century buttresses that span fifteen metres each, the same Ravy whose south wall of the choir screen you saw inside.