Gaasbeek Castle (), today a national museum, is located in the municipality of Lennik in the province of Flemish Brabant, Belgium. The fortified castle was erected around 1240 to defend the Duchy of Brabant against the County of Flanders. The castle was destroyed however by Brussels city troops in revenge for the assassination of Everard 't Serclaes, which was commanded by the Lord of Gaasbeek.