Princess Charlene of Monaco, Queen Letizia of Spain, and Queen Mathilde of Belgium met Pope Leo XIV in Vatican City's St Peter's Square following his historic inauguration mass on Sunday.

Charlene, Letizia, and Mathilde looked equally stunning in all-white ensembles at the event.

The three royals are allowed to wear white in front of the Pope because they are Catholic Queens and Princesses.

They are each one of only seven women in the world who have 'the privilege of the white' – or the ability to wear white when meeting with the Pope.

Called le privilége du blanc in French or il privilegio del biacno in Italian, the special tradition is extended solely to designated Catholic queens and princesses and is reserved for important events at the Vatican, such as private audiences, canonisations, beatifications, and special masses.

Normal protocol for papal audiences requires that ladies wear a long black dress with a high collar and long sleeves and a black mantilla.