Archivo General de Simancas
TThe doyen of Spanish archives. Founded centuries ago, its vast holdings encompass everything from financial records documenting the successive holders of Juros (an early form of state-issued debt) the inheritances of which can be very useful for genealogy, to memorials requesting aid for aged and infirm soldiers, in an era before the establishment of military pensions. I have worked at this archive many times, unearthing fascinating details of long-ago families whose stories would have vanished were it not for their financial transactions. Contact me to discuss possible research there.