Anvaing Castle, Medieval castle in Frasnes-lez-Anvaing, Belgium.

Anvaing Castle is a red-brick château rebuilt in 1561 on a rectangular plan, with grey stone window surrounds and a steep slate roof topped by three slender spires. A square tower projects on the right, and a dark wooden door opens at the water level of the former moat, now a pond fed by the Rhosnes.

A castle existed here by 1127, though little is known of the buildings before the 1561 reconstruction. The de Roubaix family held it before the de Lannoy family, who still own it. It was heavily altered around 1800, and on 28 May 1940 the Belgian capitulation was signed in its library.

The castle is the main residence of the de Lannoy family, whose descendants still live there; Stéphanie de Lannoy, who married Grand Duke Guillaume V of Luxembourg on 20 October 2012, grew up here. The interior is French in style, with several salons and a staircase in Empire style. Since 2022 vines have been planted on a south-facing slope of the estate.

The castle is a private residence and is not open to the public, so visits are limited to views from outside. The moat and ponds are fed by the Rhosnes, and the water level reaches the dark wooden door in the brick facade. The 18th-century French-style gardens were laid out for Marquis Jean de Mesgrigny.

A German officer fired a shot into the air to celebrate the 1940 capitulation; the bullet hole is still visible in the leather-covered coffered ceiling of the dining room. The room where the protocol was read in twenty minutes is the castle library.