Cadillac introduced this huge V-16 car in 1937. This was a car that was made in limited numbers and was meant only for the rich & famous and heads of states. 

This rare Cadillac V16 limousine was purchased in 1938 by an Italian Countess Rosario de Larraechea de Schiffner who was the widow of a rich German Baron Friedrich von Schiffner. The car was shipped from the GM plant in USA to Naples by sea. The Countess used this car to travel to Rome, where her daughter lived.

Upon the death of the Countess, this Cadillac was willed to one Cardinal Spellman who gladly accepted the limousine and commissioned it to the Vatican Motor Pool. This was at a time when Pius XII was the Pope.

There's no record of Pope ever riding this car, but it remained with the Vatican for a very long period before it was sold to bespoke jeweller firm owner Nicola Bulgari.