s if they were motes,
and standing on them while in motion. I have seen one marked with the
name of the builder of the church (CON_stantine_); it was so huge that
all kinds of animals had bored their holes and nests in it. The holes
looked like small caverns, many yards long, and gave shelter to
thousands of rats." Grimaldi climbed the roof at the beginning of
1606, and describes it as made of three kinds of tiles,--bronze,
brick, and lead. The tiles of gilt bronze were cast in the time of the
emperor Hadrian for the roof of the Temple of Venus and Rome. Pope
Honorius I. (625-640) was allowed by Heraclius to make use of them for
S. Peter's. The brick tiles were all stamped with the seal of King
Theodoric, or with the motto BONO ROMAE (for the good of Rome). The
lead sheets bore the names of various Popes, from Innocent III.
(1130-1138) to Benedict XII. All these precious materials for the
chronology and history of the basilica have disappeared, save a few
planks from the roof, with which the doors of the modern church were
made.

Another sight must have struck the pilgrim as he first crossed the
threshold, that of the "triumphal arch" between the nave and the
transept, glistening with golden mosaics. We owe to Prof. A. L.
Frothingham, Jr., of Baltimore, the knowledge of this work of art, he
having found the description of it by cardinal Jacobacci in his book
"De Concilio" (1538). The mosaics represented the emperor Constantine
being presented by S. Peter to the Saviour, to whom he was offering a
model of the basilica. It was destroyed, with the dedicatory
inscription, in 1525.[83]

The baptistery erected by Pope Damasus after the discovery of the
springs of the Aqua Damasiana, and restored by Leo III. (795-816),
stood at the end of the north transept.[84] One of its inscriptions
contained the verse--

"Una Petri sedes unum verumque lavacrum,"--

an allusion both to the baptismal font and to the "chair of S.
Peter's," upon which the Popes sat after baptizing the neophytes. The
cathedra is mentioned by Optatus Milevitanus, Ennodius of Pavia, and
by more recent authors, as having changed place many times, until
Alexander VII., with the help of Bernini and Paul Schor, placed it in
a case of gilt bronze at the end of the apse. It has been minutely
examined and described several times by Torrigio, Febeo, and de Rossi.
I saw it in 1867. The framework and a few panels of the relic may
possibly date from apostolic time