The GR 129 traverses Belgium from Bruges to the Ardennes and showcases the finest countryside and hills Flanders and Wallonia have to offer. Its 573 km of waymarked trails make it the longest hiking route in Belgium.

The Flemish section of the trail starts in Bruges at the Vesten, broad green ramparts around the city. From there, it runs across West Flanders along straight country roads and through marshes, nature reserves and several forests. In East Flanders, the path traverses the Leie valley and continues to Oudenaarde. Along the banks of the river Scheldt, you enter the Flemish Ardennes, where narrow paths lead you over the hills to the hamlet of Louise-Marie (Maarkedal). There, the GR 129 crosses over into Wallonia and guides you via Ath and Bergen through the Meuse valley to Dinant. Finally, you cross the natural regions of the Condroz, Famenne, Ardennes, Gaume and the Land of Arlon to arrive in the city of Arlon.

Flemish television producer Arnout Hauben travelled across Belgium on the GR 129 and turned his journey into a television series, which can be watched on (in Dutch).