Parroquia San Ignacio de Loyola

This guide to Parroquia San Ignacio de Loyola in Buenos Aires starts with a workman's pick striking a hollow spot beneath the floor in 1980, opening a stairway into tunnels nobody had mapped and nobody can fully explain. Built by Jesuit priests in the early 1600s and consecrated in 1734, the church has survived revolutions, invasions and the expulsion of the Jesuits who built it, and you'll hear the competing theories locals still argue over for what those tunnels beneath your feet were really built to hide. Stand at the south tower, where lookouts once watched the river for enemy sails.