By Duncan Kennedy
BBC News, Rome
Benedict will be only the second Pope to visit Rome's synagogue
Pope Benedict is due to make an historic visit to Rome's synagogue - only the second time a Pope has made such a trip.
Pope Benedict's visit is aimed at cementing sometimes fractious relations between Catholicism and Judaism.
But it comes amid controversy over Pope Benedict XVI's plans to turn his wartime predecessor into a saint.
Some Jewish groups plan to boycott the event because they say Pope Pius XII didn't do enough to stop the Holocaust.
Rome's synagogue is the spiritual home of the oldest Jewish community in the world outside Israel.
The event is another gesture of reconciliation between the two faiths - but it comes amid a atmosphere of mistrust.
The reason for that is Pope Benedict's plan to press ahead with moves to canonise Pius XII, who was Pope during World War II.
That has offended many Jewish people who say Pius didn't speak out forcefully enough against the Holocaust.
The Vatican says the records show he did help many Jews, but some Jewish leaders are boycotting the papal visit as they believe the Catholic Church is misguided and insensitive.