Notice an abundance of piercingly green decorations in your local grocery store? Seen any double rainbows lately? Saint Patrick’s Day is right around the corner, taking place on March 17th and many will wear green and eat an unusually large bowl of Lucky Charms to celebrate, but not many know of how the holiday came to be.

Originating in Ireland, St. Patrick’s Day is a celebration of St. Patrick, a beloved patron saint. He was born in Roman Britain but was enslaved in Ireland for several years. His notability comes from how he escaped from slavery and then returned, converting the Irish to Christianity and building the community around him through churches and schools. Word quickly spread of the wonderous St. Patrick, causing the creation of the holiday we all know and love in modern times.

Although, the traditional value of the holiday is often overlooked, it’s usually associated with green, but the original color mark of St. Patrick’s Day was blue. This is most likely due to Irish citizens immigrating to America, bringing a distorted version of the holiday with them. Despite the differences, both Ireland and outsiders have come to appreciate the new version and celebrate it regardless.

One city that goes all out for St. Patrick’s Day is Chicago, Illinois. They, however, celebrate it on March 11th rather than March 17th, dyeing the Chicago River green each year. Some have come to criticize this, as the dye used is harmful to the marine life living in it. Friends of the Chicago River, an environmentalist group, were vocal about their condemnation in 2015. Executive Director, Margaret Frisbie, went on to say, “I think it sends a message to people that the river is not alive. Can you imagine there are actually beavers living there? Because there are. You would never do that to a beaver. … Dyeing the river green does not respect that resource.” Despite the comment, the Chicago River is set to be dyed once again this year.

St. Patrick’s Day has blossomed into a very diverse holiday with a rich history. No matter how you celebrate, with homemade corned beef or a McDonald’s Shamrock Shake, the annual celebration has brought Irish cheer to many.