Vaticanus, Codex

is said to be the oldest extant vellum manuscript. It and the
Codex Sinaiticus are the two oldest uncial manuscripts. They
were probably written in the fourth century. The Vaticanus was
placed in the Vatican Library at Rome by Pope Nicolas V. in
1448, its previous history being unknown. It originally
consisted in all probability of a complete copy of the
Septuagint and of the New Testament. It is now imperfect, and
consists of 759 thin, delicate leaves, of which the New
Testament fills 142. Like the Sinaiticus, it is of the greatest
value to Biblical scholars in aiding in the formation of a
correct text of the New Testament. It is referred to by critics
as Codex B.