Columbus Day is an interesting holiday to consider because it means different things to different people. Some people consider it a day commemorating the discovery of a new world, while others see it as the enslavement of a people.
As an exercise:
Think about what your character would be doing today? Would they be at work? Home with their family eating a big meal? Stuck in traffic as the parade goes by? In the parade? Participating in a protest? Watching a Tom Selleck movie? Watching a Gerard Depardieu movie? Or on a boat recreating a great adventure?
By taking a minute to consider how your character spends a holiday, or just what they do on their day off, you can learn important information about what’s important to them.