This harks back to an ancient practice, then involving the pope and his clergy, gathering daily for Holy Mass at various churches in Rome in honor of the martyrs whose blood nourished the seeds of faith. When I say ancient, I mean it: this dates back to the 2nd or 3rd century -- meaning not very long after Peter himself!
This tradition petered out (pardon the pun) over the years, until the priests and seminarians connected with the North American College revived it in recent years. There appears to be alternate versions of who initiated it -- seminarians, or priests doing advanced study in Rome. In any case, the tradition is carried on by the NAC seminarians (here are details, plus a history, at their site).
One difference is that the successor of Saint Peter does not lead this; and another is that where it used to take place in the evenings, it now takes place each morning at 7 am. While all the seminarians take part on Ash Wednesday, for the rest of Lent, it's at the initiative of the seminarians.
Today I joined them in the visit to the Basilica of Saint Paul "outside the walls," where the remains of the Apostle rest beneath the altar to this day. The stalwart seminarians usually walk or ride their bikes; but as Saint Paul's is over 3 miles from the college, another priest and I who went together, humbly chose to forego the glory of walking, and took a bus. A few minutes after six am we caught the bus at the foot of the Gianicolo Hill, on which the North American College sits, and as the morning light began to creep over the city, we enjoyed the luxury of an almost empty bus. When we arrived, a number of seminarians had already arrived, some at least by bike. We had seen others walking as we rode by.
There were between 20 and 30 concelebrating priests, plus two deacons. Our principal celebrant was Cardinal James Harvey, an American, who is also the "archpriest" of the basilica. Another cardinal was present, but I don't know who he was. I didn't meet either.
(This is an opportunity to explain that among other things, that when a cleric -- usually, but not always, a bishop -- is made a cardinal, that means he's now a member of the clergy of Rome -- and he is assigned to a church in Rome. This harks back to the origins of the college of cardinals as essentially an institution of the city of Rome, because it was about choosing a bishop for Rome, which has now become an international institution.)
The turnout for this was rather nice; in addition to the NAC community, there were many other folks who came. And, it turned out the Beta College -- which is kind of the British counterpart to the NAC -- joins in for this Mass. This likely explains the pleasant surprise of the distinctive accents of the readers, one of the deacons, and some of the priests.
Sorry about no photos, but I thought it would be distracting to snap pictures, even before Mass, when people were trying to pray. In any case, you can easily excellent photos of the basilica online.
Before the final blessing, one of the principal concelebrants turned out to be the rector of the Beta College, and invited everyone for breakfast. "Only 100 yards away," he explained; so the priest who bussed down with me -- another Cincinnati priest -- and I decided to see what sort of English breakfast might be had in Rome, instead of caffe e cornetto at a nearby bar (again, not what you think!) as originally planned.
Well, it was a rather nice breakfast, once we got there. The rector said something like, out and to the left, but when we left the basilica, we weren't certain the door we'd chosen was the "out" he'd had in mind. But we made it. The refectory of the Beta College wasn't as large as that of the NAC, and there was quite a crowd. Somehow, however, we found a place. We had juice and coffee, bread, butter, jam, cornetti; there were hard-boiled eggs somewhere, but I never figured that one out. At our table we chatted with a Sister of Mercy from the U.S. who teaches at the Beta College, a young woman studying theology at the Angelicum (I never learned where she was from), the British vice-rector, and some assorted other folks from various places.
As Americans, we can take particular pride here, because it was our guys here who revived this lovely tradition. Consider that this begins with Ash Wednesday, meaning it can be, even in Rome, rather chilly at 5 or 5:30 am; and they have full schedules after this. You may find that when you visit Rome, you appreciate some time with other Americans, and the friendly hospitality of these fine fellows will warm your hearts; they'll make you feel right at home.