One of the air vents for the crypt in St. Peter’s Basilica, Rome, 2012.
“There are over 100 tombs within St. Peter’s Basilica (extant to various extents), many located in the Vatican grotto, beneath the Basilica. These include 91 popes, St. Ignatius of Antioch, Holy Roman Emperor Otto II, and the composer Giovanni Pierluigi da Palestrina. Exiled Catholic British royalty James Francis Edward Stuart and his two sons, Charles Edward Stuart and Henry Benedict Stuart, are buried here, having been granted asylum by Pope Clement XI. Also buried here are Maria Clementina Sobieska, wife of James Francis Edward Stuart, Queen Christina of Sweden, who abdicated her throne in order to convert to Catholicism, and Countess Matilda of Tuscany, supporter of the Papacy during the Investiture Controversy. The most recent interment was Pope John Paul II, on 8 April 2005. Beneath, near the crypt, is the recently discovered vaulted fourth-century “Tomb of the Julii”.” Source.