From its source on the edge of the Sonian Forest, the Woluwe has shaped the urban landscape through both buildings and boulevards. Old houses on the valley slopes, large estates and more recent buildings on the valley floor reveal very different aspects and architectures. This walk follows the Woluwe: first invisible, vaulted beneath the feet between Rue Middelbourg and Boulevard du Souverain, then brought back into the open near the former La Royale Belge, and finally flowing freely, sometimes hidden by lush vegetation, sometimes concealed behind houses.