The Archivo General de Indias is a monolithic 16th century construction that houses a hugely valuable collection of documents detailing the centuries of Spanish rule in the Americas and the Philippines. The building is astonishingly designed, a real success story of Renaissance architecture that would be a must-see with or without the archive that lies inside. Almost 50,000 documents wait inside, and while many are filed away for safe-keeping there is more than enough to cause mouths to open wide. That is centuries of colonial history after all.