Every March 17, revelers the world over take a slightly different meaning to “going green” and celebrate Saint Patrick’s Day.
The holiday began as a Christian feast day in honor of Maewyn Succat, a fifth-century Catholic cleric later known as Patricius. Revered for his rumored purging of snakes from Ireland—there never were any—and his fabled use of the shamrock to explain the Holy Trinity to Irish pagans, Patricius was considered the “Apostle of Ireland” by the seventh century C.E., and he became a potent symbol of Ireland for believers and nonbelievers alike.
Now a worldwide celebration of Irish identity, Saint Patrick’s Day’s origins as a green holiday are rather murky. Saint Patrick was originally associated with the color blue, and the cross of Saint Patrick, on the United Kingdom’s “Union Jack” flag, is white and red. But by the early 1600s, Saint Patrick’s Day had become inextricably linked to the green shamrock, leading to the modern emerald-hued celebration.
Today, National Geographic celebrates Saint Patrick’s Day with a look at our favorite photos featuring the the color green.