The Sonian Forest is a vast forest area in the heart of Belgium.
Immerse yourself in an endless beech forest with trees like cathedrals. Walk on wide hiking trails or narrow, winding paths that find their way through small valleys with streams and lakes.
Discover a mysterious stone circle and a dolmen, two very special memorials.
Bring your own picnic into this large forest, because along the way you will find only trees and greenery.
The Sonian Forest
The Sonian Forest is located in the heart of Belgium, just south of the capital Brussels. It is located on the territory of the Flemish, Walloon and Brussels regions. This beautiful forest is no less than 44 km2.
This vast forest area is a remnant of the primeval forest that stretched from the North Sea to the Rhine in Roman times. Julius Caesar named this forest the "coal forest" (Silva Carbonaria) because coal burners were at work. They burned charcoal to extract iron from ferrous sandstone.
Until the end of the Middle Ages, the intact forest was the property of the nobility and several monasteries. But in the 16th century, the Austrian Habsburgs had the trees replaced by planted beech trees. These beech trees still form the "beech cathedral": an open forest with giant beech trees that can be up to 200 years old. Some of these giants are uprooted in stormy weather, you will find quite a few fallen trees along the way.
Today, nature management replaces part of the beech trees with a more varied forest with a higher ecological value.
The walk
The walk plunges you into the beech forest. Do not expect beautiful views in such a forest, but the green security of a vast forest area.
The Sonian Forest has always been covered with trees and agriculture has never been practiced. As a result, you can always recognize the natural relief in the forest. There are wide hiking trails on flat ridges where you can quickly make for miles. And there are narrow, winding paths in shallow valleys with streams and ponds. In the cathedral forest with giant beech trees you can see quite far through the trees. Where these giants have been replaced by more varied forests, you look no further than a few meters away.
The walk passes two remarkable monuments, which form a quiet harmony with the forest that surrounds them.
The memorial to the victims of the attacks of March 22, 2016 commemorates the 32 victims with as many beech trees. They stand in a circle around a ring of stone, Belgian blue stone. The monument to foresters who died during the First World War commemorates 12 victims with the same number of megaliths. These are also in a circle, with a dolmen in the middle. The stones consist of the same conglomerate that was used in Wéris in prehistoric times.
This walk takes place more than 99% on unpaved roads and only crosses a highway twice. The route avoids bridle paths (which are often made of loose sand) and bike paths (which are usually paved).
When
In the Sonian Forest you can take a nice walk at any time of the year.
In spring, there is a lot of light, and the beech trees turn fresh green. During the summer, there is not much sun under the tall trees, but it remains beautiful and cool. In autumn, the trees look beautiful when the leaves fade. Mushrooms grow everywhere, and you can pick chestnuts at two places along the road. On rainy winter days, the trees provide enough shelter to keep it a little dry.
The Sonian Forest is a nature reserve, so you should not pay attention to striking hunters. To spot wildlife, you need to get out early in the morning. Wild boars are very shy, but with a little luck you can see deer.
This forest is the garden of all Brussels residents, so it is very busy, especially during the weekend. Fortunately, the area is very large and it becomes much quieter as you move away from the capital.
Point of departure and arrival
Groenendaal Castle
Address: Duboislaan 1, 1560 Hoeilaart
- By car: there is ample parking.
- By public transport: smooth rail link from Brussels to Groenendaal station. Then another 1.5 km walk to Groenendaal Castle.
Practical information
At Groenendaal Castle there is the trendy tavern 'Sonian' where you can eat and drink something.
Not far from the starting point is the forest museum 'Jan van Ruusbroec' where you will learn all about the Sonian Forest. You also get a free map of the Sonian Forest with all hiking trails. You can also find this map in PDF on the website of the Sonian Forest:
For those who find the Sonian Forest too far away for a day trip: there is a B&B near the beginning of the walk. For accommodation, you can also go to a hotel near Groenendaal train station.
This walk is part of a series of high-level hikes in Flanders.
There is always a variant of +/- 12 km and one of +/- 20 km.
Difficulty level: Hard (83/100)
Length: 20.5 km
Duration: 04h05
Total ascent: 186 m
Maximal slope: 4.08 %
Average slope: 0.91 %
Net ascent: 0 m
Total descent: 186 m
Difficulty level according to the author: 3/10
Paved roads: 970 m (5 %)
Cobblestones: 0 m (0 %)
Car free roads: 13.6 km (66 %)
Noise pollution
Amount of traffic
Natural area
Urban area
Water rich area
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