This is a vestige of the marshy areas that formerly bordered on the course of the Geleytsbeek. It combines two types of landscapes: a rural environment made up of marshes and vegetable gardens and a wooded setting. The Keyenbempt site, a “clay meadow”, was already occupied by humans in the Mesolithic era. At the time of regionalisation, the Brussels-Capital Region inherited it, and cleanup works were completed in 2007.

Keyenbempt offers visitors a mosaic of very different spaces and ambiances. The 700 m course of the open waters of the Geleytsbeek constitutes its backbone. There are a marsh, three areas of vegetable gardens, mowed meadows and a wooded hill.

Its subsoil has great archaeological value. A shelter for hibernation of bats, a sort of bunker carpeted with greenery, has been set up not far from the vegetable gardens. The site also accommodates a beehive. Despite the recent development of the site, frogs and dragonflies already abound there. In the woods, it is not unusual to see a red squirrel.

The differentiated management applied by Brussels Environment makes the site accessible to the public while preserving plant regeneration and helping it evolve toward a mixture of indigenous species.