The intimate Oratorio della Purità has a beautiful, dramatic ceiling painting of the Assumption by Giambattista Tiepolo, and eight biblical scenes in chiaroscuro by his son, Giandomenico, on the walls. The building was built as a theatre in 1680 but the patriarch of Aquileia ordered its transformation 80 years later, repulsed by such a devilish institution so close to a cathedral.
