The Basilica of Sacré-Cœur crowns Montmartre, a hill long associated with quarrying, religious houses, rural life, and the traditional martyrdom of Saint Denis. Its creation followed France's defeat in the Franco-Prussian War of 1870–1871 and the upheaval of the Paris Commune. Catholic laymen Alexandre Legentil and Hubert Rohault de Fleury vowed to build a sanctuary to the Sacred Heart as an act of penitence and national renewal. The proposal reflected a growing devotion that linked personal piety with conservative ideas about France's moral condition.

The National Assembly declared construction a matter of public utility in 1873, enabling acquisition of the hilltop land. Because the Commune had begun on Montmartre in 1871, later critics interpreted the church as expiation for revolutionary rebellion and for the state's bloody repression. The original vow preceded the Commune, but political language surrounding the project often fused defeat, revolution, and sin. Sacré-Cœur consequently became a monument contested between Catholic, monarchist, republican, socialist, and secular visions of the nation.

Architect Paul Abadie won a competition with a Romanesque-Byzantine design that differed sharply from Paris's Gothic churches. The cornerstone was laid in 1875. Unstable gypsum quarries beneath the site required dozens of deep shafts filled with masonry and concrete before the superstructure could safely rise. Abadie died in 1884, and several architects modified and completed the project. Château-Landon travertine, which releases pale calcite when wet, gave the exterior its persistent whiteness. Private donations from millions of contributors financed much of the long campaign.

Worship began before the building was complete, and perpetual Eucharistic adoration has continued since 1885. The dome was finished around the turn of the century, the great Savoyarde bell entered service, and the campanile followed. Construction was substantially complete in 1914, but the First World War delayed consecration until 1919. Inside, Luc-Olivier Merson's enormous apse mosaic of Christ in Majesty, completed in the 1920s, turned the sanctuary's national vow into a glittering visual program of church, saints, and France.

Sacré-Cœur became inseparable from the modern identity of Montmartre. Pilgrims, parishioners, tourists, street performers, and political demonstrators use the hill and steps in different ways. The basilica's silhouette offers sweeping views and inspired other twentieth-century churches, while opponents continue to see it as a symbol of reaction or of silenced Communard memory. Nearby Square Louise-Michel, named for the revolutionary activist, places competing histories in the same landscape rather than resolving the conflict.

The basilica was classified as a historic monument in 2022, renewing debate over heritage and politics. It remains an active Catholic sanctuary whose liturgy and continuous prayer coexist with intense tourism. Conservation addresses stone, mosaics, roofs, security, and crowding, while interpretation must acknowledge both devotion and controversy. Sacré-Cœur is not simply a white landmark built after war. It is a material argument about defeat, repentance, authority, secularism, and memory, repeatedly reinterpreted by the city it overlooks. Its hilltop presence forces Paris to live with disagreement in public view. The monument's preservation is strongest when historical explanation allows prayer, architectural achievement, Communard grief, and republican criticism to remain visible together.