Watermael-Boitsfort in the context of "Sonian Forest"

The Woluwe (French: [wolywe]; Dutch: [ˈʋoːlyu.ə]) is a stream that flows through several municipalities in the south-east and east of Brussels, Belgium, and is a right tributary of the Senne in Vilvoorde. The Kleine (little) Maalbeek is a tributary of the Woluwe in Kraainem. Many ponds formed along the stream over time, among which the Mellaerts Ponds still exist. The valley of the Woluwe crosses the municipalities of Auderghem, Watermael-Boitsfort, Woluwe-Saint-Pierre, Woluwe-Saint-Lambert, Kraainem, Zaventem, Machelen and Vilvoorde.

The towns of Woluwe-Saint-Pierre, Woluwe-Saint-Lambert and Sint-Stevens-Woluwe derive their name from it.

Auderghem (French, pronounced [odœʁɡɛm] ; former Dutch spelling) or Oudergem (Dutch, pronounced [ˈʌudərɣɛm] ) is one of the 19 municipalities of the Brussels-Capital Region, Belgium. Located in the south-eastern part of the region, along the Woluwe valley and at the entrance to the Sonian Forest, it is bordered by Etterbeek, Ixelles, Watermael-Boitsfort, and Woluwe-Saint-Pierre, as well as the Flemish municipalities of Tervuren and Overijse. In common with all of Brussels' municipalities, it is legally bilingual (French–Dutch).

Despite large roads slicing through and the increasing traffic, the municipality has an environmental advantage, and it has been able to preserve a relatively important part of its natural and historic legacy: the creeks, Rouge Cloître Abbey and its art centre, the Priory of Val-Duchesse, the Château of Trois-Fontaines, the Château Saint-Anne, and St. Anne's Chapel.

Uccle (French, pronounced [ykl(ə)] ) or Ukkel (Dutch, pronounced [ˈʏkəl] ) is one of the 19 municipalities of the Brussels-Capital Region, Belgium. Located in the southern part of the region, it is bordered by the City of Brussels, Forest, Ixelles, and Watermael-Boitsfort, as well as the Flemish municipalities of Drogenbos, Linkebeek and Sint-Genesius-Rode. In common with all of Brussels' municipalities, it is legally bilingual (French–Dutch).

As of 1 January 2022, the municipality had a population of 85,099 inhabitants. The total area is 22.87 km (8.83 sq mi), which gives a population density of 3,720/km (9,600/sq mi), half the average of Brussels. It is generally considered an affluent area of the region, and is particularly noted for its community of French immigrants.

Ixelles (French, pronounced [iksɛl] ) or Elsene (Dutch, pronounced [ˈɛlsənə] ) is one of the 19 municipalities of the Brussels-Capital Region, Belgium. Located to the south-east of Brussels' city centre, it is geographically bisected by the City of Brussels. It is also bordered by the municipalities of Auderghem, Etterbeek, Forest, Uccle, Saint-Gilles and Watermael-Boitsfort.

As of 1 January 2023, the municipality had a population of 88,521 inhabitants. The total area is 6.41 km (2.47 sq mi), which gives a population density of 13,807/km (35,760/sq mi). In common with all of Brussels' municipalities, it is legally bilingual (French–Dutch). It is generally considered an affluent area of the region, and is particularly noted for its communities of European and Congolese immigrants.