L'armoire de fer (French: 'iron chest') in general refers to an iron chest used to house important papers. A notable and frequent use of the term refers to a hiding place at the apartments of Louis XVI of France at the Tuileries Palace where some secret documents were kept. The existence of this iron cabinet, hidden behind wooden panelling, was publicly revealed in November 1792 to Jean-Marie Roland, vicomte de la Platière, Girondin Minister of the Interior. Source: Wikipedia (en)