From Posadas, undulating RN 12 climbs and dips northeast over leached red earth past several Jesuit mission ruins, the best-preserved of which is San Ignacio Miní. Though less well-preserved, Santa Ana and Loreto both have their assets, but progress in restoration has nearly ceased.

Founded in 1637, Santa Ana once sustained a Guaraní population of more than 4,000, though more than half departed within two decades after the Jesuits’ expulsion. Only the mission walls remain, some still covered by strangler figs and with other aggressive vegetation wedged between the cracks. Immediately alongside it, the disconcertingly open crypts and coffins of an abandoned 20th-century cemetery are a reminder that the Jesuit experiment was only the first failed settlement here.

Work at Loreto, which dates from 1632 but moved here only in 1660, has lagged behind that of Santa Ana, but plaques with descriptive quotations from Jesuit priests help visitors imagine what the site might have been. In 1700, Martirologio Romano (Roman Martyrology), the first book ever published within what is now Argentina, was printed here. It later appeared in Guaraní.

Getting to Santa Ana and Loreto

Santa Ana is 43 kilometers east of Posadas and one kilometer southeast of RN 12 via a dirt road that can get muddy; the junction is clearly marked, and buses from Posadas will drop passengers here. Hours are 7 a.m.–6 p.m. daily; the US$7 admission charge is valid for 15 days and applicable to the province’s other Jesuit ruins.

The Loreto turnoff is at Km 48, five kilometers beyond that to Santa Ana, but the site itself is three kilometers farther south of RN 12. Both sites have small museums and cafés.