The Capuchin Crypt, located beneath the church of Santa Maria della Concezione dei Cappuccini, is one of the most unique and haunting sites in Rome. The crypt holds the skeletal remains of approximately 3,700 Capuchin friars. When the Capuchin friars relocated here in 1631, they brought with them cartloads of bones from the old cemetery, which were then arranged into elaborate designs to decorate the crypt. The soil used in the crypt was transported from Jerusalem, further adding to its sacred nature.

The crypt consists of several chapels where bones are arranged in intricate patterns, including the Crypt of the Skulls, Crypt of the Pelvises, and Crypt of the Three Skeletons. Each arrangement serves as a meditation on mortality, with inscriptions reminding visitors of the inevitability of death. The adjoining museum offers further context, showcasing artifacts related to the Capuchin friars, including a painting by Caravaggio depicting Saint Francis.

Visitors can also view the Mass Chapel, which does not contain bones but serves as a space for prayer. The Capuchin friars intended the crypt to be a reflection on the brevity of life, and it has become a deeply spiritual site for many.