This church dates from the 13th century, when its ossuary was used to bury plague victims from nearby San Barnaba hospital. It was rebuilt in rococo style in 1679, after it collapsed beneath the fallen bell tower of adjacent Santo Stefano. The walls of the new ossuary, with its frescoed vault, Triumph of Souls among Flying Angels, are now lined with a macabre flourish in human bones, finished with the skulls of condemned prisoners.