In 1902, a mortuary chapel was built in the lower level of the cathedral. Contained within this chapel are vaults buried underneath the floor in front of the altar. These vaults contain the bodies of former Bishops and Archbishops of Dubuque. Four of Dubuque's Archbishops are buried elsewhere. Also buried in the chapel is Archbishop Raymond Ettledorf - a local priest who became Nuncio to New Zealand and parts of Africa. The altar and communion rail are made of Italian marble.