In studying any group of people in the past, it is natural to ask where they were active and how big their community was. For Rome's fourth-century Christians who are my subject, a good authority to answer both questions was and still is Richard Krautheimer. I remember him well, and two of his younger associates, Alfred Frazer and "Gus" Corbett. He and his team, over the course of forty years from the 1930s on, produced a set of five splendid volumes on the history and construction of the city's early basilicas.1
Krautheimer was especially struck by the dimensions of the buildings he studied and what they showed about the size of the city's congregation. From the period before 312, archaeology still can provide no generally accepted example of the socalled house churches, set either in private residences or in commercial premises; nor do we have any remains of the parish churches which got their name tituli from the plaques above their doors, and which gradually replaced house churches. Of early tituli, we know fifteen or more through written sources. Others were gradually added, many in a form still surviving and thus open to our estimate of their size.2 Their total even at the end of the fourth century remained, as Krautheimer says, "amazingly small," and they seem to have been, in his words, no more than "modest halls."3 On average they might have held 250 or 300 worshippers apiece, in their pre-Constantinian dimensions, if they were as large as those post- Constantine that survive to be measured. Collectively that would mean around forty-five hundred persons. If this represented the entire Christian population in a city of half a million we can understand Krautheimer's surprise.4
Was construction limited by a lack of funds? Apparently not. The extent of building is apparent in our sources beginning in 312. With a coreligionist on the throne in that year-and, moreover, one who had in his hand the spoils of a civil war-suddenly the Christian community was rich, and Constantine was more than open to suggestions from their leader about the spending of those spoils.5 A request for a residence, a papal palace adjoining a cathedral church, was predictably submitted and approved6-so also, that this church should be dedicated to the Savior with silver statues of Christ prominent within. It was also natural that a great building should be raised to St. Peter on whose connection with Rome rested the primacy of its bishop.
Yet the Lateran and the Vatican basilicas together provided new room for no more than fifty-two hundred worshippers, an "astonishingly limited provision" in Krautheimer's words.7 That is a first oddity. A second is surely the construction of St. Peter's in a cemetery, however natural this seems today.
As to these two surprising matters, first, regarding the quite limited increase in space made available to the laity, a model can be offered that includes various obstructions and areas reserved to clergy and liturgical procedures. How it would look can be shown in S. Giovanni.
Five-meter squares are marked off for ease of comprehension, with human figures drawn to scale. How much space each would need may be left for explanation elsewhere;8 but we may count no more than 150 seated in the middle of the nave and another 2,000 who stood, if they were so close-packed as the sample showing them in one corner of the church. All together, they cannot have amounted to more than 2,200. In St. Peter's we may imagine another 3,000-hence my suggested total of 5,200 for both basilicas, a figure arrived at by the same method I used also for the tituli.
As to the second matter of surprise, namely, the choice of a cemetery as the site for St. Peter's: however strange this was to Roman ideas of public honoring, we should recall the report that the bishop Fabian (236-250) "directed many buildings, fabricae, to be put up" in the cemeteries. What were those buildings, I wonder? …