1 Grosso - Antonio Barberini Sede Vacante

Sede Vacante coinage was struck under the authority of the Apostolic Camera during the interregnum following a pope's death, with the Cardinal Camerlengo holding administrative power over the Papal States until a new pontiff was elected. In 1655, that office was occupied by Antonio Barberini the Younger, nephew of Urban VIII, a man whose family had spent the previous pontificate accumulating wealth and enemies in roughly equal measure. The Barberini fled Rome under Innocent X and only returned under Clement IX — Antonio's presence as Camerlengo in 1655 marked a cautious rehabilitation.

The conclave that followed lasted just five days and elected Fabio Chigi as Alexander VII.