Exactly one hundred years ago, the surface area of the City of Brussels was increased threefold following the annexation of the municipalities of Laeken, Haren and Neder-Over-Heembeek and the municipalities of Schaerbeek and Molenbeek-Saint-Jean.

This annexation was to have a significant impact on the urban landscape of the city. It also had a major effect on the administration which was to undergo profound changes. As independent municipalities, Laeken, Haren and NOH (otherwise known as Neder-Over-Heembeek) had all the administrative services necessary to ensure the operation of a municipality.

After the death of Emile Bockstael in 1920, the last mayor of Laeken, the town was administered by its first alderman, Joseph Van de Meulebroeck.

The municipal elections of 24 April 1921 led to the merger of the administrations. The Mayor of the City of Brussels, Adolphe Max thus became the mayor of this whole new area. However, it was divided into two districts. The first included the City of Brussels in its former guise; the second included the area of Laeken, Neder-Over-Heembeek, Haren and the parts of the municipalities of Schaerbeek and Molenbeek-Saint-Jean. The division into two districts is characterised by the maintenance of civil status registers and the assignment of a civil registry alderman for the second district.

The number of aldermen was increased from five to seven. An alderman was selected from the municipal councillors elected by each of the districts. The new college of alderman comprised Maurice Lemonnier, Louis Steens, Jules Coelst (Laeken), Emile Jacqmain, Joseph Van de Meulebroeck (Laeken), André Brassine, Paul Auguste Wauwermans. An alderman carried out the role of the alderman of the civil registry in each district: this task was allocated to Louis Steens, for the first district and Jules Coelst for the second district.

The number of municipal councillors has increased considerably to 50, according to the proportion of one councillor per 4,500 inhabitants or for a fraction of 4,500 inhabitants greater than 2,500. This increase led to changes to the town hall meeting room as the benches became too small to accommodate all of the members.

The merger of the municipalities did not pose any particular problems for the municipal representatives, however it was quite a different story for the administrative functions. Each municipality had a municipal secretary and a municipal collection agent. These positions disappeared with the annexation and provision were made in the law. The communal secretary was given the choice between retiring or obtaining an equivalent job with guaranteed salary and benefits.

The municipal collection agents and all appointed members of staff of the incorporated municipalities were included in a special framework ensuring the right to remuneration and benefits acquired; they would be gradually integrated into the staff of the City of Brussels as and when vacancies arose.

Staff working on 1 January 1921 became part of the administrative staff.

The property belonging to the administration of the hospices and to the charity offices of the annexed municipalities were now managed by the administration of the Hospices et Secours of the City of Brussels. The appointed staff members were employed by the administration of the Hospices et Secours of the City of Brussels.

The territories of Laeken, Haren and NOH were purely and simply annexed to the City of Brussels. The incorporation of the areas of Schaerbeek and Molenbeek-Saint-Jean was settled by means of compensation, the amount of which was fixed by mutual agreement between each of the municipalities and the City of Brussels.

The territorial changes also had an impact on the boundaries of judicial cantons. The judicial canton of Laeken have become the fourth judicial canton of Brussels.

As such, it now served the former municipalities of NOH and Haren as well as parts of the municipalities of Schaerbeek and Molenbeek-Saint-Jean.

The number of notaries, fixed according to the number of inhabitants, has also been modified. It was increased to 45 for the City of Brussels and 7 in the canton of Molenbeek-Saint-Jean.

The law made no pronouncement on the integration of schools into the education system of the City of Brussels nor on the new police divisions.