Photo de stock - The citadel is now the Archivo General del Reino, to which the national archives of Spain were removed by order of Philip II in 1563 Their transference thither was first suggested to Charles V by Cardinal Ximenes de Cisneros The extensive alterations were made by three celebrated 16th century architects, Juan de Herrera, Alonso Berruguete and Juan Gómez de Mora, the arrangement of the papers was entrusted to Diego de Ayala They occupy forty-six rooms, and are arranged in upwards of 80,000 bundles 33,000,000 documents, including important private as well as state papers The castle of Simancas is located near the city of Valladolid, Spain It was built as a defensive fortress by the Moorish in the 9th century, and was later converted into a prison At the end of the 15th century, Queen Isabella I and King Ferdinand V bought the castle, and their grandson, Charles, later converted it into the royal archive In 1564 it was remodelled under Spanish architect Juan de Herrera and became known as the General Archive of Simancas This historic archive is the largest in Spain and second in Europe only to the Vatican Library It contains more than 30 million documents dating from the 15th to the 19th centuries.