Château de Losange, Castle in the Ardennes forest near Bastogne, Belgium.

Château de Losange is a white-plastered castle in the Ardennes forest at Losange, near Villers-la-Bonne-Eau in Luxembourg province, Belgium. Its central block has three storeys under a dark grey hipped roof, with two small octagonal cupolas behind the front eaves. A taller square pavilion with a steep pyramidal roof and lantern stands at the left end, a shorter pavilion with a small cupola closes the right, and a single-storey annex with a rounded doorway projects at the far left.

An original structure was built in 1529 at a water site, but the current building took shape in the early 18th century under Herman de Trappé. Following wartime destruction, it was completely restored and updated during the 1920s.

The castle became widely known from 1999 as the home of Count Patrick d'Udekem d'Acoz and his wife, parents of Queen Mathilde, wife of King Philippe. Mathilde spent her whole childhood here. Its current owner is her brother Charles Henry d'Udekem d'Acoz.

The château is private property and its interior is not open to visitors; the white facade, the pavilions and the hipped roof can be seen from outside the grounds. It stands in the middle of the Ardennes forest at Losange, near the small village of Villers-la-Bonne-Eau in the province of Luxembourg, reached by forest roads.

The castle is linked to Belgium's royal family: Queen Mathilde, wife of King Philippe, spent her entire childhood here. Her parents, Count Patrick d'Udekem d'Acoz and his wife, owned it from 1999; the count died in 2008. The present owner is her brother Charles Henry d'Udekem d'Acoz.