The Castle of Burgos was a castle and alcázar, located in the city of Burgos, in the hill of San Miguel to 75 metres (246 ft) above the city and to 981 metres (3,219 ft) above the sea. This hill was the subject of archaeological surveys by General Centeno in the years 1925 and 1926 trying to find Napoleonic military files from when the French in their retreat blew up the fortress. According to the results obtained in this excavation the origin of the castle dates to the Visigoths, and its oldest parts, to the Romans.