According to a widespread, persistent, and entirely unfounded legend, the menorah and other ritual objects from the Second Temple remain hidden in the secret archives of the Catholic Church in Rome. While the Vatican in fact possesses no such artifacts, it does posess an impressive trove of rare Hebrew manuscripts—including volumes of Talmud, ancient and medieval Bible commentaries, liturgical poetry, and much else. There is nothing secret about these texts, however: they were microfilmed for the use of the National Library of Israel in the 1950s, and Jewish researchers have had regular access to them since. Lawrence Schiffman describes the collection and explains its history:
Many of the manuscripts are beautifully illuminated, having been copied in the Middle Ages and during the Renaissance (i.e., from the 9th to the 16th century). The collection includes a manuscript that is probably the earliest Hebrew codex (bound book) in existence: a copy of the Sifra [a halakhic exegesis of Leviticus] dating from the end of the 9th century or the first half of the 10th. . . . There are well over 50 codices of biblical texts, excluding small fragments, among them a copy of the entire Tanakh written around 1100 in Italy. . . . No other collection includes as many copies of tractates of the Talmud as the Vatican Library.
Over the course of the 16th century, cardinals, bishops, and popes occasionally contributed various Hebrew books, which numbered 173 by the 1640s. A few manuscripts were transferred from the estates of converts or sold by Jewish vendors to Christian collectors. . . . In 1472, the city of Volterra was laid to waste by the forces of Count Federico of Urbino. Among the victims of the indiscriminate pillaging was the wealthy merchant Menahem ben Aharon Volterra, whose Hebrew manuscripts were secured by Federico himself for his personal library. In 1657, the collection of the dukes of Urbino became part of the Vatican Library.
[W]hile we can never be sure how the previous owners got their manuscripts, the Vatican did not pillage them from Jews. What we can say is that if these manuscripts had been in the hands of Jewish institutions, they would certainly have been stolen by the Nazis.