I didn't appreciate until recently that the calendar we live by today was personally designed by Julius Caesar. Like not by some forgotten technocrats incidentally during his time, but Julius Caesar himself as a subject matter expert, as a side-project. With consultation, certainly, but by his initiative, from long-standing engagement with the problem in one of his early jobs from long before he was a main character…
Pope Gregory has entered the chat
there have been some changes to the calendar since Caesar, especially when people went to bed Thursday 4 October 1582 and woke up on Friday 15 October 1582, and thereafter there were no more leap years on centuries except every 400 years.
https://www.onthisday.com/articles/gregory-conquers-julius-c...