Heukelum Castle, locally known as Kasteel Heukelum or Kasteel Merckenburg, lies east of the town with the same name, in the Gelderland province in the Netherlands.
Heukelum Castle is also known as Merckenburg Castle.
The castle was first mentioned in 1272. It was then owned by the Van Arkel family. During the 14th century the castle was destroyed and rebuilt. In 1567 the castle went from the Van Arkel family to the De Thiennes family, who were also Counts of Rumbeke in present Belgium.
In 1672 the castle was destroyed by the French troops which left the castle as a ruin.
In 1734 the De Thiennes' sold the remains of the castle to the Van der Stel family. They built the present castle, incorporating the (probably) 13th century gate tower of the earlier castle.
Between 1788 and 1813 the castle was owned by the Van Gennep family. During the 20th century the castle was inhabited by Baron RA. van Heeckeren van Brandenburg.
The castle is surrounded by a moat. The castle and its outbuildings are private property and thus not accessible.