Kasteel Terlinden, 18th-century castle in Aalst, Belgium.

Kasteel Terlinden is an 18th-century castle on the west side of Aalst, built in 1775 as a U-shaped house on a rectangular island in the middle of a rectangular pond. Its red brick walls rise straight from the water, banded with lighter stone and pierced by rows of rectangular windows under a steep dark roof with a small pointed tower and a domed corner turret. A lower round brick wing with a tall arched window and a conical roof adjoins it, facing a lawn.

Kasteel Terlinden is an 18th-century castle: in 1775 Jaak Angelus Dierickx, president of the Council of Flanders, replaced a farmstead with a U-shaped castle on a rectangular island in a rectangular pond. After the French Revolution he fled in 1794 and the castle was seized as a headquarters for the garde magasin des vivres. In 1913 the Geerinckx family rebuilt the main block in neotraditional style, adapting the two 1775 side wings and the gatehouse.

Aalst locals call Terlinden the "Kasteel van Verdoemenis" (Castle of Damnation), a nickname tied to the Jansenist priest Pasquier Quesnel, who stayed here and wrote his book "Motif de droit du père Quesnel". The name stuck in popular storytelling, and the castle is still identified with it today.

Kasteel Terlinden stands on the west side of Aalst, at Jacques Geerinckxsquare and Raffelgemstraat, with the pond and lawn visible from the public park around it. The castle itself is not open as a museum; the orangery serves as a branch of the Aalst city library. The park, reduced to about 2 hectares, is open to the public.

Aalst locals long called Terlinden the "Kasteel van Verdoemenis" (Castle of Damnation) because the Jansenist priest Pasquier Quesnel stayed here and wrote his book "Motif de droit du père Quesnel". The nickname stuck to the estate, not to any religious architecture on the building itself.