Calendar data for all known observances

I’m looking for calendaring data, specific about days that are observed on a regular basis, such as “holidays”.

Every since I was a kid I thought, “One day I’ll have a calendar that tells me everything anyone hold special about that day, so I may know about more people in the world.”

And now Clover has started using the Calendar app, and I am greatly motivated to collate/build such a tool. And for that I need data. A lot of data. Let’s go find it. :slight_smile: