After The Bones of St. Peter, John Evangelist Walsh (1982)
The outlines of the present basilica (in brown) show its immense size compared to the fourth-century basilica (in green) built by Constantine. An ancient Roman burial ground (in blue) lies beneath both churches. The high altar of Constantine’s church (and later Michelangelo’s) is positioned directly over a dirt grave that was clearly thought to be Peter’s.