Basilica of the Sacred Heart in Brussels

The National Basilica of the Sacred Heart (French: Basilique Nationale du Sacré-Cœur; Dutch: Nationale Basiliek van het Heilig-Hart) is a Roman Catholic Minor Basilica and parish church in Brussels. The church was dedicated to the Sacred Heart, inspired by the Basilique du Sacré-Coeur in Paris. Symbolically King Leopold II laid the first stone of the basilica in 1905 during the celebrations of the 75th anniversary of Belgian independence. The construction was halted by the two World Wars and finished only in 1969. Belonging to the Metropolitan Archbishopric of Mechelen-Brussels, it is one of the ten largest Roman Catholic church by area in the world.

Located in the Parc Elisabeth atop the Koekelberg Hill in Brussels' Koekelberg municipality, the church is popularly known as the Koekelberg Basilica. The massive brick and concrete reinforced church features two thin towers and a green copper dome that rises 89 metres above the ground, dominating the northwestern skyline of Brussels.

Mid-19th century, King Leopold I dreamed of turning the uninhabited Koekelberg hill into a royal residence area. In 1902, King Leopold II visited the Basilique du Sacré-Coeur of Paris and decided to build a pilgrimage church, a national sanctuary dedicated to the Sacred Heart of Jesus. The initial project of Leuven-based architect Pierre Langerock was a sumptuous neo-gothic church inspired by the "ideal cathedral" of Eugène Viollet-le-Duc. Only the foundations had been finished when World War I broke out. After the war, it was impossible to resume Langerock's plan due to the state of public finances. A project by architect Albert Van Huffel was adopted. The unfinished church was consecrated in 1935. The cupola was finished in 1969 and, in 1970, the ceremony for the 25th anniversary of the episcopate of Archbishop of Mechelen-Brussels Cardinal Leo Joseph Suenens marked the completion of the construction of the Basilica.

The final design by architect Albert Van Huffel won the great architecture prize at the Exposition Internationale des Arts Décoratifs et Industriels Modernes in Paris.

The church, on Koekelberg hill, is a landmark on the Brussels skyline. It is the largest building in Art Deco style in the world, at 89 m high and 164.5 m long. The cupola platform affords an excellent city panoramic view of Brussels and the wider area of Flemish-Brabant. The central nave is 141 m long, and at its widest the building is 107 m. The cupola has a diameter of 33 m. The church accommodates 3500 people.

The building combines reinforced concrete with terracotta layering, bricks, and dimension stone. Belgian painter Anto Carte designed the eight stained glass windows representing the life of Jesus.

This enormous building houses Catholic Church celebrations in both main Belgian national languages (Dutch and French), as well as conferences, exhibitions (as in 2007–2008, the International Leonardo da Vinci Expo), a restaurant, a Catholic radio station, a theatre and two museums.