Kauwberg, Protected nature area in Uccle, Belgium.

Kauwberg is a 53-hectare semi-natural green space in Uccle, Brussels, made up of an old sand quarry, meadows, woods and marshes. A railway line, line 26 from Schaerbeek to Hal, crosses the lower part of the site, and Avenue Dolez runs along the heights, separating the main area from several wooded hills of sand and spoil. A wire fence on thin wooden posts crosses the grassland, with a cut stump near it.

Formerly part of the Sonian Forest, the site was cleared in the 19th century for pastures and sand and loam quarries used in brick-making. Urbanisation projects between the 1970s and 1990s failed, and part of the meadows reforested naturally. In 1994, thanks to the SOS Kauwberg association, 22 of the 54 hectares were classified; in 2001 the whole site was designated green space in the regional plan. Since 2020, dead trees have been felled and the Geleytsbeek marsh reopened with an observation pontoon.

The name Kauwberg is a compound of the Dutch words for jackdaw and hill, though the sources do not record a jackdaw colony here. What visitors can still see are the vegetable gardens and a few houses on the edges of the site, alongside meadows where cattle and horses were kept.

The site lies east of Sauvagère park and the Verrewinkel cemetery; Avenue Dolez crosses its heights and separates the main area from the wooded hills of sand and spoil. Railway line 26 from Schaerbeek to Hal runs through the lower part, where earthworks have reshaped the ground. Paths were reworked from 2020 and a boardwalk now overlooks the reopened Geleytsbeek marsh.

By 2029 Brussels Environment plans to turn the site into a refuge for wild bees by felling trees and stripping the humus layer so the bare sand is exposed again. The former sand quarry and the marsh of the Geleytsbeek, reopened with an observation pontoon from 2020, are the habitats most closely watched.