Consecrated in 1658, the Chiesa del Purgatorio miraculously survived the earthquake of 1693 before being tweaked and expanded the following century. These 18th-century additions include the bell tower and facade, the latter's two false doors a constant reminder that there is only one way to heaven. Go through the right door and you'll be rewarded with Francesco Manno's Anime in Purgatorio (Souls in Purgatory; 1800), located at the main altar.
The square facing the church is known locally as Piazza degli Archi (Square of the Arches), named for the aqueduct that ran past here before the earthquake of 1693.