Chapultepec Castle overlooks the park of the same name. The fort, built in 1785 on a promontory, was a major centre of power, and the residence of the Emperor Maximilian, Porfirio Díaz and successive Presidents of the Republic up to Lázaro Cárdenas in 1940. It now contains the collections of the Museo Nacional de Historia. Outside, the monument to the Niños Heroes recalls the struggle of six cadets - a military school was located in the castle at the time - who died fighting against North American forces on 13 September 1847.