Solvay Castle (French: Château Solvay, also called Château de La Hulpe), is a château located in the municipality of La Hulpe, Walloon Brabant, Belgium.The château was built by the Marquis Maximilien de Béthune. Jean-Jacques Arveuf-Fransquin of France and the Belgian architect Jean-François Coppens (1799–1873) were given the task of building the castle, which was completed in 1842.