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Monaco's royal couple got into the spirit of the German beer extravaganza, complete with Bavarian costume and hefty tumblers of amber nectar.
They toasted their health, wealth and one year of marriage before gulping down their beer with gusto, thereby declaring the party well and truly underway.
Oktoberfest is the world's biggest festival and now takes place in cities all over Europe. It has become a crucial event that celebrates German culture, cuisine and heritage.
Charlene and Albert's presence at the Monegasque branch of the event caps an eventful week for the couple.
On Wednesday, they were enjoying La Dolce Vita in Italy, attending the glittering Ballo de Giglio gala in Florence. The black-tie ball donates proceeds to Prince Albert's foundation.
Before their romantic night of dancing, husband and wife had taken in the sights of the beautiful European city, arriving in the historic Palazzo Vecchio to a passionate Italian welcome.