Brazil (South - Rio Grande do Sul)
Jesuit missions and Iraí
For much of the seventeenth and eighteenth centuries, the Guaraní Indians of what is now northeastern Argentina, southeastern Paraguay and northwestern Rio Grande do Sul were only nominally within the domain of the Spanish and Portuguese empires, and instead were ruled – or protected – by the Society of Jesus, the Jesuits. The first redução – a self-governing Indian settlement based around a Jesuit mission – was established in 1610 and, within a hundred years, thirty such places were in existence. 
With a total population of 150,000, these mini-cities became centres of some importance, with erva maté and cattle the mainstay of economic activity, though spinning, weaving and metallurgical cottage industries were also pursued. As the seventeenth century progressed, Spain and Portugal grew increasingly concerned over the Jesuits’ power, and Rome feared that the religious order was becoming too independent of papal authority. Finally, in 1756, Spanish and Portuguese forces attacked the missions, the Jesuits were expelled and many Indians killed. The missions themselves were dissolved, either razed to the ground or abandoned to nature, surviving only as ruins.

Brazil, Argentina and Paraguay each have one fine ruin of a Jesuit mission and, without too much difficulty, it’s possible to combine a visit to all three. There are direct bus services every day between Santo Ângelo, which serves the São Miguel site in Brazil, and Posadas in Argentina, crossing the border at São Borja. Posadas is a short distance from Argentina’s San Ignacio Miní ruins and Paraguay’s Trinidad. Alternatively, these latter two missions are an easy side-trip from the Iguaçu falls; the superb country hotel Estancia Las Mercedes, roughly midway between the two areas near Eldorado, makes a convenient base.