Thus, none of the four
or five hundred volumes on the topography of ancient Rome speaks of
the basilicas raised by Constantine; of the church of S. Maria
Antiqua, built side by side with the Temple of Vesta, the two worships
dwelling together as it were, for nearly a century; of the Christian
burial-grounds; of the imperial mausoleum near S. Peter's; of the
porticoes, several miles in length, which led from the centre of the
city to the churches of S. Peter, S. Paul, and S. Lorenzo; of the
palace of the Caesars transformed into the residence of the Popes. Why
should these constructions of monumental and historical character be
expelled from the list of classical buildings? and why should we
overlook the fact that many great names in the annals of the empire
are those of members of the Church, especially when the knowledge of
their conversion enables us to explain events that had been, up to the
latest discoveries, shrouded in mystery?

It is a remarkable fact that the record of some of these events should
be found, not in church annals, calendars, or itineraries, but in
passages in the writings of pagan annalists and historians. Thus, in
ecclesiastical documents no mention is made of the conversion of the
two Domitillae, or Flavius Clemens, or Petronilla, all of whom were
relatives of the Flavian emperors; and of the Acilii Glabriones, the
noblest among the noble, as Herodianus calls them (2, 3). Their
fortunes and death are described only by the Roman historians and
biographers of the time of Domitian. It seems that when the official
_feriale_, or calendar, was resumed, after the end of the
persecutions, preference was given to names of those confessors and
martyrs whose deeds were still fresh in the memory of the living, and
of necessity little attention was paid to those of the first and
second centuries, whose acts either had not been written down, or had
been lost during the persecutions.

As the crypt of the Acilii Glabriones on the Via Salaria has become
one of the chief places of attraction, since its re-discovery in 1888,
I cannot begin this volume under better auspices than by giving an
account of this important event.[2]

In exploring that portion of the Catacombs of Priscilla which lies
under the Monte delle Gioie, near the entrance from the Via Salaria,
de Rossi observed that the labyrinth of the galleries converged
towards an original crypt, shaped like a Greek [Greek: G] (Gamma), and
decorated with f