Kasteel Obbeek near Heusden-Zolder is a classical manor house built around 1750 by Charles-Antoine de Horion near the Mangelbeek creek. Despite its 'castle' name—attributed to its striking contrast with surrounding farmers' clay dwellings—it is architecturally a refined manor rather than a fortified stronghold. The property gained historical significance when Horion's son led local resistance during French rule and later served as mayor during the United Kingdom of the Netherlands period. The manor and its surrounding landscape were formally protected as a monument in 2004.
