Loreto, founded in 1632, has few visible remains but is atmospheric. There are plans for further excavation and restoration, but for now the jungle is king here and for the most part it’s difficult to interpret the tumbled mossy stones among the trees, so the free guided tour is worthwhile. It was one of the more important missions; a printing press was built here, the first in the southern part of the continent.
Unlike at San Ignacio and Santa Ana, here you'll enter the site from the back passing through the workshops before coming to the church. There are knotted trees growing on top and through several of the walls which will appeal to visitors with archaeological fantasies keen to imagine stumbling across ruins in the jungle.