Several attributes set it apart from the earlier Romanesque style, including its pioneering use of the rib vault and flying buttress, its enormous and colourful rose windows, and the naturalism and abundance of its sculptural decoration.

It still contains Gothic, Baroque, and 19th-century sculptures, 17th- and early 18th-century altarpieces, and some of the most important relics in Christendom, including the crown of thorns, and a sliver and nail from the True Cross.

[21] The chronicler Jean de Saint-Victor [fr] recorded in the Memorial Historiarum that the construction of Notre-Dame began between 24 March and 25 April 1163 with the laying of the cornerstone in the presence of King Louis VII and Pope Alexander III.

Art historian Andrew Tallon has argued, based on detailed laser scans of the entire structure, that the buttresses were part of the original design.

And although some speakers, by their own free judgment, because [they are] able to see only a few things easily, may say that some other is more beautiful, I believe, however, respectfully, that, if they attend more diligently to the whole and the parts, they will quickly retract this opinion.

[39] Louis Antoine de Noailles, archbishop of Paris, extensively modified the roof of Notre-Dame in 1726, renovating its framing and removing the gargoyles with lead gutters.

Supervising a large team of sculptors, glass makers and other craftsmen, and working from drawings or engravings, Viollet-le-Duc remade or added decorations if he felt they were in the spirit of the original style.

[47] The decoration of the restoration included a bronze roof statue of Saint Thomas that resembles Viollet-le-Duc, as well as the sculpture of mythical creatures on the Galerie des Chimères.

In 1963, on the initiative of culture minister André Malraux and to mark the 800th anniversary of the cathedral, the façade was cleaned of the centuries of soot and grime, restoring it to its original off-white colour.

[58] A decade-long renovation programme began in 1991 and replaced much of the exterior, with care given to retain the authentic architectural elements of the cathedral, including rigorous inspection of new limestone blocks.

[66][67] The entire renovation was estimated to cost €100 million, which the archbishop of Paris planned to raise through funds from the national government and private donations.

[68] A €6 million renovation of the cathedral's flèche began in late 2018 and continued into the following year, requiring the temporary removal of copper statues on the roof and other decorative elements.

[72] French police arrested two people on 8 September 2016 after a car containing seven gas canisters filled with diesel fuel was found near Notre-Dame.

[73][74] On 10 February 2017, French police arrested four people in Montpellier known to have ties to radical Islamist organisations on charges of plotting to travel to Paris and attack the cathedral.

[97] The law, which passed on 11 May 2019, was hotly debated in the French National Assembly, with opponents accusing Macron's administration of using Notre-Dame for political grandstanding, and defenders arguing the need for expediency and tax breaks to encourage philanthropic giving.

Even before the competition rules were announced, architects around the world offered suggestions: the proposals included a 100-metre (330 ft) flèche made of carbon fibre, covered with gold leaf; a roof built of stained glass; a greenhouse; a garden with trees, open to the sky; and a column of light pointed upwards.

In December 2019, Monseigneur Patrick Chauvet, the rector of the cathedral, said there was still a 50% chance that Notre-Dame could not be saved due to the risk of the remaining scaffolding falling onto the three damaged vaults.

[107] On 10 April 2020, the archbishop of Paris, Michel Aupetit, and a handful of participants, all in protective clothing to prevent exposure to lead dust, performed a Good Friday service inside the cathedral.

[116] On 14 April 2022, France's National Preventive Archaeological Research Institute (INRAP [fr]) announced that the sarcophagus was extracted from the cathedral and that scientists had examined the casket using an endoscopic camera, revealing the upper part of a skeleton.

Pope Francis declined an invitation from Macron to attend the reopening, holding a consistory in Rome to create 21 new cardinals on that day and planning a visit to the French island of Corsica the following week.

"[125] Jean-Michel Guilemont of the French Ministry of culture responded, "The interior elevations will regain their original colour, since the chapels and side aisles were very dirty.

The stairway has 387 steps, and has a stop at the Gothic hall at the level of the rose window, where visitors could look over the parvis and see a collection of paintings and sculpture from earlier periods of the cathedral's history.

The Gothic cathedral was a liber pauperum, a "poor people's book", covered with sculptures vividly illustrating biblical stories, for the vast majority of parishioners who were, at the time, illiterate.

[132] The tympanum over the central portal on the west façade, facing the square, vividly illustrates the Last Judgment, with figures of sinners being led off to hell, and good Christians taken to heaven.

[137] The two transept windows are larger and contain a greater proportion of glass than the rose on the west façade, because the new system of buttresses made the nave walls thinner and stronger.

The new windows, made by Jacques Le Chevallier, are without human figures and use abstract designs and colour to try to recreate the luminosity of the cathedral's interior in the 13th century.

After the death of Pierre Cochereau, the cathedral authorities controversially decided to return to the Clicquot practice of having several titulaires, and also to guarantee that no one organist would have so much influence over the organ.

In addition to accompanying regular activities at the cathedral, the bells have also rung to commemorate events of national and international significance, such as the armistice of 11 November 1918, the liberation of Paris, the fall of the Berlin Wall, and the September 11 attacks.

[147] By the end of the 14th century the bells were marking the civil hours, and in 1472 they began to call to prayer for the Angelus three times a day, both practices which continue today.

Shortly after the fire, French clockmaker Jean-Baptiste Vior discovered an almost identical 1867 Collin-Wagner movement in storage at Sainte-Trinité Church in northern Paris.