A: Città del Vaticano, Vatican City
The writings of Roman grammarian, rhetorician and advocate, Marcus Cornelius Fronto, were
"cut to pieces in the Dark Ages. Any author may fall on hard times, when parchment is scarce and other texts are more in demand, but to Fronto belongs the unique distinction of surviving solely as the lower script in no fewer than three palimpsests, which range in date from about 350 to 475.
"The first preserves a few words from the end of his Gratiarum actio pro Cathaginiensibus. It is part of that remarkable manuscript Vatican, Pal. lat 24, which is a tissue of ancient codices, largely of classical authors and Italian in origin, which were reused in Italy to make up a copy of the Old Testament. The Fronto fragment (ff. 45 and 53, CLA I. 72) is written in rustic capitals of s. IV-V [4th to 5th centuries]; the text was discovered by Angelo Mai in 1820 and published by him in 1823.
"The extensive remains of Fronto's Correspondence are transmitted as the lower script of Milan, Abros. E. 147 sup. + Vatican lat 5750, written in an uncial hand of the later fifth century, presumably in Italy; it was rewritten in the seventh century, probably at Bobbio, where it was later housed, with a Latin translation of the Acts of the Council of Chalcedon. Both parts were discovered by Mai, the Ambrosian in 1815, the Vatican in 1819, and published in 1815 and 1823 respectively. The first, in particular, suffered disastrously from his heavy use of chemical reagents.
"It seemed, until 1956, that further gains to Fronto's text could come only from strenuous emendation and decipherment; but in that year Bernhard Bischoff pointed out that a third manuscript, published as early as 1750 and conjecturally ascribed to Fronto (then undiscovered) by Dom Tassin in the Nouveau traité de diplomatique, contained fragments of Epit. ad Verum 2.1 which actually overlap with the Milan palimpsest. This is one leaf of Paris lat 12161 (pp. 133-4,CLA v. 629) rewritten probably at Corbie, the late seventh or early eight century with Jerome and Gennadius, De viris illustribus. The original script, a sixth century uncial, may perhaps belong to southern France, in which case we have what could be a remnant of the last flowering of rhetorical studies in Gaul" (Reynolds ed., Texts and Transmission  173-74).