At the end of his life, King Leopold II decided in 1900, to give the nation the lands, castles and buildings that he had acquired over the previous years.
He put three conditions on this donation: the land and buildings could never be sold, and some of them would have to retain their function and original appearance and be at the disposal of the successors to the throne.
The main properties which were originally part of the trust were, for example, the park and Castle of Laeken, the Greenhouses of Laeken, the Castles of Stuyvenberg and Ciergnon, Parc Duden in Forest and the Arboretum in Tervueren.
At present, the Royal Trust is an autonomous public institution with its own legal personality. Financially, it is completely independent: it accounts for its own income and expenditure, and manages its own assets and staff.
Part of the properties are at the disposal of the King, such as the park of Laeken, the Castles of Belvédère, Stuyvenberg, Ciergnon and Fenffe, but other properties like offices in Brussels or agricultural land are rented out in order to generate income for the Trust.