The General Archive of Simancas (also known by its acronym, AGS) is an official archive located in the castle of Simancas, province of Valladolid, Spain. It was founded in 1540, making this the first official archive of the Crown of Castile.
The chronological evolution of the institution has been influenced by the history of the Crown of Castile. The moments of strength or withdrawal of the Spanish monarchy were reflected in the form of documents arrivals or resource shortages. A major milestone occurred in 1588, when Philip II of Spain gave the instruction to the Government of the Archives of Simancas, a key document for understanding the management of both this file and others in the peninsula. Also, the damage suffered during the Spanish War of Independence had a major impact on what is now the institution.
Currently, the AGS is a cultural institution under the Ministry of Culture of Spain dedicated to conservation, cataloging and investigation with the large funds that are hosted there. These activities have brought about the reputation of the archive as one of the cornerstones of the Iberian Peninsula in what is relates to preservation and custody of documents.
The archive was placed in Simancas, a town some 10 km away from Valladolid. The place was not chosen randomly but was selected a fortified and easily defended. During the period of the Reconquista, the village of Simancas was relevant as a frontier zone. Subsequently, its strategic location between the kingdoms of León and Castile gave it a political role in that period. After the conquest of Toledo and its territory in 1085 the town lost its importance, and in the 13th century was just one of many towns in the outskirts of Valladolid. However, it soon ceased to be part of the jurisdiction of Valladolid, because in 1465 King Henry IV of Castile rewarded the city of Simancas to remain faithful to him.