National treasures are cultural objects that  have a major interest to the national heritage regarding history, art or archeology. They have been subjected to a temporary refusal to exit the country through a "refusal certificate in accordance with the amended law No 92-1477 of December 31th 1992. archeology, have been subject to a temporary refusal to exit the country through a "refusal certificate" in accordance with the law n°92-1477. To date, more than 30 major works were concerned by these measures, including "Tête en profondeur" (Head in depth) by Julio González.