The Catacombs of the Capuchin Convent are a 17th-century underground cemetery carved out of tuff. It contains 8,000 embalmed corpses that lived between the 17th and 19th century. It is a 300 square metre structure divided into four corridors: priests, men, women and professionals. The entrance is on the left side of the main façade of the Chiesa della Madonna della Pace. The bodies, dressed in period clothing, are identified by name, surname and date of death. The professionals’ corridor also houses the embalmed body of the painter Velasquez.
Little is known about the method the Capuchin friars used to preserve the corpses. It was common to dry the corpses naturally in drip pans. Then they were washed with vinegar, exposed to the open air for a few days. Finally, they were covered and placed in niches or wooden boxes. Those who died of epidemics were instead bathed in arsenic and milk of lime.