[1] The basilica was first proposed by Felix Fournier, the Bishop of Nantes, in 1870 after the defeat of France and the capture of Napoleon III at the Battle of Sedan in the Franco-Prussian War.

He attributed the defeat of France to the moral decline of the country since the French Revolution, and proposed a new Parisian church dedicated to the Sacred Heart of Jesus.

[4] The proposal to build a new Parisian church dedicated to the Sacred Heart of Jesus was first made on September 4, 1870, by Felix Fournier, the Bishop of Nantes, following the defeat of France and the capture of Emperor Napoleon III by the Prussians at the Battle of Sedan in the Franco-Prussian War.

[4] In January 1871, Fournier was joined by the philanthropist Alexandre Legentil, who was a follower of Frédéric Ozanam, the founder of the Society of Saint Vincent de Paul.

Legentil declared that France had been justly punished for its sins by the defeat of the French Army at Sedan and the imprisonment of the Pope in Italy by Italian nationalists.

To make honourable amends for our sins, and to obtain the infinite mercy of the Sacred Heart of our Lord Jesus Christ and the pardon of our sins, as well as extraordinary aid which alone can delivery our sovereign Pontiff from captivity and reverse the misfortune of France, we promise to contribute to the erection in Paris of a sanctuary dedicated to the Sacred Heart of Jesus.

Since the location included land belonging to the local government as well as private owners, the French parliament assisted in securing the site by declaring that the construction of the basilica was in the national interest.

[5] In July 1873, the proposal was finally brought forward and approved in the National Assembly with the official statement that "it was necessary to efface by this work of expiation the crimes which have crowned our sorrows.

His tomb became the site of the Basilica of Saint Denis, the traditional resting place for the kings of France until the French Revolution.

In addition, Montmartre was the birthplace of the Society of Jesus, one of the largest and most influential religious orders in the history of the Catholic Church.

Eighty-three wells, each thirty meters deep, had to be dug under the site and filled with rock and concrete to serve as subterranean pillars supporting the basilica.

[10] Construction costs, estimated at 7 million francs drawn entirely from private donors, were expended before any above-ground structure became visible.

[11] Not long after the foundation was completed in 1884, Abadie died and was succeeded by five other architects who made extensive modifications: Honoré Daumet (1884–1886), Jean-Charles Laisné (1886–1891), Henri-Pierre-Marie Rauline (1891–1904), Lucien Magne (1904–1916), and Jean-Louis Hulot (1916–1924).

In 1882, the walls of the church were barely above its foundations when the left-wing coalition led by Georges Clemenceau won the parliamentary election.

For the Revolution, for a century of free speech and science, and emancipated reason... for that they built this gigantic landmark that Paris can see from all of its streets, and cannot be seen without feeling misunderstood and injured.

They proposed installing a full-size copy of the Statue of Liberty on top of Montmartre, directly in front of the basilica, which would entirely block the view of the church.

Lionel Jospin, socialist Prime Minister between 1997 and 2002 also expressed his wish that the basilica be demolished as a symbol of "obscurantism, bad taste and reactionism.

This decision was immediately attacked by the leftist politician Jean-Luc Mélenchon, who called it "a glorification of the assassination of 32,000 Paris Communards shot in just 8 days".

The white stone of Sacré-Cœur is travertine limestone of a type called Chateau-Landon, quarried in Souppes-sur-Loing, in Seine-et-Marne, France.

The particular quality of this stone is that it is extremely hard with a fine grain, and exudes calcite on contact with rainwater, making it exceptionally white.

In all of the mosaic, the artists adapted elements of Byzantine art in the organization of the figures, the altered perspective, and the use of polychrome colors enhanced with silver and gold.

The top of the dome is open to tourists and affords a spectacular panoramic view of the city of Paris, which spreads out to the south of the basilica.

For example, the Chapel of the Order of Notre Dame of the Sea is decorated with tapestries illustrating Christ walking on the water and the Miraculous Catch of fish.

In the centre of the crypt is the chapel of the Pieta, whose central element is a monument statue of the Virgin Mary at the foot of the cross, at the altar.

The organ was ahead of its time, containing multiple expressive divisions and giving the performer considerable advantages over other even larger instruments of the day.

One exception was on the night of August 24, 1944 when La Nueve – 9th Company, Régiment de marche du Tchad of the French 2nd Armored Division – broke into Paris and arrived at the Hôtel de Ville during the Liberation of Paris from Nazi German occupation, becoming the first French Army troops to return to the city since 1940.

The church is dedicated to the Sacred Heart of Jesus, which was an increasingly popular devotion after the visions of Saint Margaret Mary Alacoque (1647–1690) in Paray-le-Monial.

Since 1885 (before construction had been completed) the Blessed Sacrament (Christ's body, consecrated during the Mass) has been continually on display in a monstrance above the high altar.

[31] Tourists and others are asked to dress appropriately when visiting the basilica and to observe silence as much as possible, so as not to disturb persons who have come from around the world to pray in this place of pilgrimage, especially since the Blessed Sacrament is displayed.

[32] A much smaller version of the basilica, Sacré-Cœur de la Balata, is located north of Fort-de-France, Martinique, on N3, the main inland road.