the prosperity which led to the period of its greatest splendour. The Puerto de Indias in Seville became the principal port linking Spain to Latin America in 1503 with the monopoly created by the royal decree of Queen Isabella I of Castile; this granted the city exclusive privileges as the port of entry and exit for all the Indies trade. To administer this commercial activity, the Catholic Monarchs founded the Casa de Contratación, or House of Trade, (though it was not then located in a specific building, its documents can now be seen in the Archive of the Indies). From here all voyages of exploration and trade had to be approved, thus giving Seville control of the wealth transported from the New World, enforced by laws regarding the contracting of voyages and which routes the ships must follow. Together the Casa de Contratación and the Consulado de mercaderes (the merchant guild founded in 1543) regulated all mercantile, scientific and judicial intercourse with the New World. Consequently, the city grew to over 100,000 inhabitants, making it the largest and most urbanised city in Spain at the time; more of its streets were bricked or paved than in any other in the peninsula. All goods imported from the New World had to pass through the Casa de Contratación before being distributed throughout the rest of Spain. A 'golden age' of development commenced in Seville, due to its being the only port awarded the royal monopoly for trade with the growing Spanish colonies in the Americas, and the influx of riches from them. Since only sailing ships leaving from and returning to the inland port of Seville could engage in trade with the Spanish Americas, merchants from Europe and other trade centers needed to go to Seville to acquire trade goods from the New World. A twenty percent tax, the quinto real, was levied by the Casa on all precious metals entering Spain. Trade with the overseas possessions was handled by the merchants' guild based in Seville, the Consulado de Mercaderes, which worked in conjunction with the Casa de Contratación. Since it controlled most of the trade in the Spanish colonies, the Consulado was able to maintain its own monopoly and keep prices high in all the colonies, and even had a part in royal politics. The Consulado thus effectively manipulated the government and the citizenry of both Spain and the colonies, and