Saint Casimir's Day is celebrated on March 4 and is most widely observed in Poland and Lithuania, where Saint Casimir is recognized as the patron saint. The day commemorates Casimir Jagiellon, a crown prince of the Kingdom of Poland and the Grand Duchy of Lithuania in the 15th century, known for his exceptional politeness, humility, and commitment to fairness and justice. He died in 1484 at the age of 26 and was canonized by Pope Clement VIII in 1602. In honor of Saint Casimir, many Roman Catholic parishes hold special Masses on his feast day. In Vilnius, Lithuania, a large folk arts and crafts fair known as Kaziuko mugė takes place on the Sunday nearest to the feast, celebrating local culture and craftsmanship. Saint Casimir's remains are interred in Vilnius Cathedral, where a miraculous painting of him, completed around 1520, is also located.