Koekelberg Basilica

Officially: the National Basilica of the Sacred Heart.

The church has the shape of a Latin cross with a central nave of 141 meters long and a transept of 107.80 meters wide. The dome has a diameter of 33 meters and a height of 89 meters. The total outside length is 164.5 meters. It is therefore the sixth longest church in the world, after the Basilique Notre-Dame de la Paix in Yamoussoukro (Ivory Coast), St. Peter's Basilica in Rome (187 m), the Cathedral Saint John the Divine in New York (183 m), Liverpool Cathedral in Liverpool (188 m), St. Paul's Cathedral in London (175 m). It is the largest Art Deco church building in the world.
The building can accommodate 3,500 people.

Due to its enormous size, parts of the basilica can be used for multiple purposes. Exhibitions take place regularly. Underground there are meeting rooms and rooms for family celebrations and conferences, as well as a theater with 228 seats (Vitta Hall) and a restaurant (Le Basilic). The Catholic Brussels radio station Radio Spes had its studio in the basement until the end of 2017. There is also a climbing wall for caving. The panorama from the gallery at the foot of the dome, about 52 meters high, offers a panoramic view of the city of Brussels and the surrounding Brabant.

The building houses two museums:
Museum of Modern Religious Art
Museum of the Black Sisters
The non-profit organization Friends of the National Basilica of the Sacred Heart Koekelberg takes care of the day-to-day management of the building.
nl.wikipedia.org/wiki/Nationale_Basiliek_van_het_Heilig_Hart

The National Basilica of the Sacred Heart, also known as the Basilica of Koekelberg, is a church on the border of Koekelberg and Ganshoren. The basilica was built between 1905 and 1970. The final version was designed by the Ghent architect Albert Van huffel. The enormous basilica - the largest church in Belgium -, built in art deco style, is a Belgian monument and is used for large celebrations, both in Dutch and French.