While traditional holidays honor famous people, historical events and momentous occasions, one day in March actually celebrates a letter in the Greek alphabet! 3/14 is Pi Day, an annual "holiday" that celebrates the mathematical symbol that represents a constant, the "ratio of the circumference of a circle to its diameter", which happens to be around 3.14159.

Founded by the Prince of Pi, physicist Larry Shaw, Pi Day was first celebrated at the San Francisco Exploratorium in 1988. People celebrated by eating fruit pies and marching around in a circular space. Today, Pi Day is celebrated all over the world. Activities include math-related events, games, exhibits, pie baking or pie eating contests and anything pi-related. In 2009, the United States House of Representatives passed House Resolution 224 designating March 14 as National Pi Day.