Château de Beusdael, Medieval castle in Sippenaeken, Belgium

Château de Beusdael stands in the hamlet of Beusdael, part of Sippenaeken in Plombières, on the Belgian border with the Netherlands, surrounded by a water-filled moat. Its monumental limestone keep, 12 m wide and 28 m high under the cornice, has walls 1.5 to 2.5 m thick and corner lookout turrets. An L-shaped wing, a chapel at the north end, a tower on the southwest corner and a gatehouse with a bridge complete the complex.

The castle was first mentioned in the 13th century as the seat of a lordship within the ban of Montzen, in the Duchy of Limburg. Around 1400, Elisabeth de Beusdael, the last heiress of that name, brought it by marriage to Jean van Eys; the van Eys family held it until the late 16th century, when Eva van Eys de Beusdael married Jean Colyn. Count Florent d'Oultremont carried out major alterations in 1882, adding a chapel, a small round tower on the courtyard, a bridge and a gatehouse.

The lords of Beusdael kept a townhouse in Maastricht, the Poort van Beusdael on Hoogbrugstraat, and held the Beusdaelshof near Bemelen; both passed with the castle to the Colyn family in 1577. The Maastricht house was sold in 1686 for 4,300 guilders and is now a national monument.

The castle is private property and not open to the public, so visits are limited to views from the Rue de Beusdael. It stands in a hollow surrounded by a water-filled moat, with the Beusdal wood to the south and southwest and the Terzieterbeek rising nearby in the Bronnetjesbosch.

The keep's walls are 1.5 to 2.5 metres thick, built of limestone, and measure 12 metres wide by 28 metres high up to the cornice. A vaulted room occupies its first floor, and lookout turrets sit on the four corners, with a bell tower in the spire.