In several churches in Rome, it was physically impossible, even before the twentieth-century liturgical reforms, for the priest to celebrate Mass facing away from the people, because of the presence, immediately in front of the altar, of the "confession" (), an area sunk below floor level to enable people to come close to the tomb of the saint buried beneath the altar. The best-known such "confession" is that in Saint Peter's Basilica, but many other churches in Rome have the same architectural feature, including at least one, the present Basilica of Saint Paul Outside the Walls, which is oriented in such a way that the priest faces west when celebrating Mass.