St. Lucia's Day, also known as Santa Lucia Day, is a Christian feast day celebrated on December 13th, primarily in Sweden, Norway, and Denmark, as well as parts of Finland. It commemorates Saint Lucy, a young Italian woman who was martyred for her faith around 304 AD. The day is known for its traditions of light, particularly candlelit processions, and the celebration of baked goods like saffron buns according to the Swedish Institute.