At least two popes have used the passage to escape danger. The first was Pope Alexander VI in 1494, who used it to flee when Charles VIII invaded the city and threatened his life. The second was Clement VII during the 1527 Sack of Rome when the city fell to Holy Roman Emperor Charles V and his troops.
Though the passage has not been used since and indeed languished in a state of disrepair for many centuries before its renovation in 2000, the Swiss Guard reportedly keeps a key on hand for the Pope, just in case…