The Basilica of the Sacred Heart of Montmartre, known as the National Vow, located at the top of the butte Montmartre, in the Clignancourt district of the 18th arrondissement of Paris (France), is a major Parisian religious building, "sanctuary of Eucharistic adoration and divine mercy ”and property of the Archdiocese of Paris.

The construction of this church, both a political and cultural monument, follows the post-war period of 1870. It is declared of public utility by a law passed on July 24, 1873 by the National Assembly of 1871; the building was officially completed in 1923. It fits into the context of sacral recharging and within the framework of a new “moral order” following the events of the Paris Commune, of which Montmartre was one of the high places. Its location at an altitude of 130 m near one of the highest points in Paris, and its dome which rises to 83 meters, make it visible from far away. With nearly eleven million pilgrims and visitors per year, it is the second most visited religious monument in Paris after the Notre-Dame de Paris cathedral.