The General Archive of the Indies (Archivo General de Indias), housed since 1785 in the 16th-century Casa Lonja de Mercaderes beside Seville Cathedral, preserves the records of the Casa de Contratación (House of Trade), the crown agency founded in Seville in 1503 to administer and monopolize Spain's trade with its American territories. As the 16th century progressed, the Casa de Contratación took on regulation of the Spanish transatlantic slave trade -- licensing shipping routes, collecting duties, and maintaining official trade records -- before relocating to Cádiz in 1717. The archive's roughly 80 million pages, spanning the 1490s to the early 19th century, constitute the principal documentary record of Spain's colonial and slave-trading administration.