In 455, the Vandals captured and looted Rome. They took many objects of art with them, including the Temple Treasure that had been in Jerusalem until the Roman commander Titus had sacked that city (in 70 CE). The Vandals took the objects to Carthage, and lost them to the Byzantines, who captured the city in 534. According to Procopius (History of the Wars, 4.9), the Jewish treasures were taken to Constantinople, where general Belisarius displayed them during his triumphal entry.
Among these were the treasures of the Jews, which Titus … had brought to Rome after the capture of Jerusalem. And one of the Jews, seeing these things, approached one of those known to the emperor and said: “These treasures I think it inexpedient to carry into the palace in Byzantium. Indeed, it is not possible for them to be elsewhere than in the place where Solomon, the king of the Jews, formerly placed them. For it is because of these that Gizeric captured the palace of the Romans, and that now the Roman army has captured that the Vandals.”
When this had been brought to the ears of the Emperor, he became afraid and quickly sent everything to the sanctuaries of the Christians in Jerusalem.
So, the treasures of the Jewish temple were returned to Jerusalem. They are not in the Vatican, as some people seem to think. I heard that urban legend for the first time in Italy, some fifteen years ago, and believed that the story, which is so flatly contradicted by a well-known and accessible ancient author, had died a well-deserved death, but I was wrong. When Benedict XVI visited Israel last spring, this myth was suddenly in the headlines again, because two pious Jews demanded that the pope would be seized and kept until the Menorah was returned. The judge dismissed the case on 11 May 2009 – unfortunately argueing that a foreign chief of state was immune, instead of saying that lunatic fringe theories ought to be ignored.
It must be noted, though, that there are other stories about the Temple Treasure. Ibn Abdelhakam writes that the Arabian conquerors of Spain found the “Table of Solomon” when they captured Toledo in 711 (History of the Conquest of Spain, 21). It was brought to Damascus. If this is a reference to the Table of the Table for the Shewbread, this suggests that at least one object was brought to Spain instead of Carthage. In any case, there is not a single piece of evidence that connects the Menorah to the Vatican.