Calendar is  As a tradition dating back to the mid-1800s, advent calendars are a truly classic holiday staple. Originally, they were designed to mark the days of “Advent”, a four week holiday period leading up to the Feast of the Nativity, which was not always on standard dates. The calendars served as the original “reason for the season” reminders in many families homes. Today, we use it as an exciting way to count up the 24 days before December 25th, our Christmas.