Signposted in light green, the Royal Walk (Koninklijke Wandeling) departs from the monument that was erected on the occasion of the 50th anniversary of the Royal Donation. Fifty beech trees were planted behind the stone bench, some of which have since disappeared. The Royal Walk forms a wide, 8-shaped loop. It largely runs along the forest road of the same name, which was built at the behest of King Leopold II during the reforestation of the domain in the 1870s.
Departing from this starting point we walk through the New World section of the arboretum, an area flanked with tree species from the Atlantic and the Pacific Basins of North America. The tree species from the north-west of the United States are on the right, the ones from the north-east on the left. Further on we pass an impressive cluster of so-called Monkey Puzzle trees (Araucarias) from Chile and Coast Redwoods (Sequoias) from California.
Having reached the intersection at Capuchin Avenue (Kapucijnendreef), a long straight avenue flanked by rows of purple beech trees, we leave the collection of the arboretum behind us. The scenic avenue connects the village of Jezus-Oak with the park in Tervuren. Having crossed it into the lane that is bordered with linden trees, we are surrounded by mixed oak forest. Further on, on the steeper slopes with sandy soils, there are mixed coniferous forests with Scots and Black pine, Douglas fir and larch. An open space is worthy of note below the so-called Keienberg area. Here we can find a restored biotope that has become utterly rare: the traditional heather of Brabant. The Sonian Forest used to have more open plains like this one on the poorest soils. They are the so-called “wastines”, desert areas that in former times were overgrazed by sheep.
At the height of the Terschurendreef, the outline of a former pond can still be discerned on the left, now completely reclaimed by the forest. Between the 16th and 19th centuries the Capuchin monastery stood on the opposite side. Founded with the support of Isabella of Spain, Sovereign of the Spanish Netherlands, it was quickly demolished by order of the French revolutionary government and not a trace of it remains above ground. The Old World section of the arboretum is on the opposite end of the Kapucijnendreef, with tree groups from Japan on one side and China on the other.
Continuing on a long and pleasant walk along arboretum groups representing Southern Europe, and along the nursery of the domain, the Royal Walk begins to close the loop and returns to the New World section. Wide and sometimes deep grass ‘valleys’ lie between the arboretum groups of the Rocky Mountains and the Sierra Nevada. In the background are the deciduous forests of eastern North America, arboretum groups that are only accessible via the meadows or forest paths.
Via the Wapenplein we follow the boundary line of the domain of the Royal Donation, back to the starting point of the walk. The evergreen coniferous forests of Western America contrast here with the typical forest vegetation found in the Sonian Forest, with its vigorous and sometimes massive beech trees.