The religious congregation of the “Black Sisters” originates from a late branch of a medieval movement called “Cellites”. Having originated in the Rhineland, this movement devoted to the ideal of poverty rapidly spread through the Low Countries. As its followers primarily cared for the plague-stricken, they could rely on huge backing from the local population.
Following the move of the cloister from the centre of Brussels in 1998, part of their legacy was handed to the association "Friends of the National Basilica of the Sacred Heart". A museum section was established to welcome the bequest of the community.