This holiday is always celebrated on 7 December.
Saint Ambrose was an archbishop of Milan during the 4th century.
He became an important ecclesiastical figure of his time and was one of the four original doctors of the Church.
Saint Ambrose was sometimes known as the 'Honey-Tongued Doctor'. He got this nickname from the story that when he was a baby, it was said that a swarm of bees started crawling around his mouth. However instead of stinging him they left honey on his lips.
This tale also explains why in addition to Milan, he is the patron saint of beekeepers and candle makers.
The Milanese love Christmas, and start the festivities early on the feast day of the city's patron saint, Saint Ambrose, with the fair known as Oh Bej! Oh Bej! literally meaning 'So beautiful! So beautiful!'.
The fair takes the form of a street market arranged around the Saint's Basilica, offering everything from antique stalls and buskers to roast chestnuts and candy floss.
The fair provides an excellent opportunity to do some Christmas shopping, and is particularly enjoyed by children.
The Saint's day also coincides with the opening of the season of the world famous Milan La Scala Opera.