5 Defunct Calendars

There are a number of different calendars used around the world today, including the Gregorian calendar (in which the current year is 2025) and the traditional Chinese calendar (in which the current year is 4723). There’s also the Julian calendar; though this was largely replaced by the Gregorian calendar, institutions like the Eastern Orthodox Church continue to use it. But other historical calendars have now entirely disappeared from daily life—here’s a look at five such creations that have become obsolete.

1. Ancient Roman Calendar
2. Coligny Calendar
3. Aztec Calendar
4. Florentine Calendar
5. French Republican Calendar

Ancient Roman Calendar

Today, most of the West uses the Gregorian calendar, which has its roots in two earlier calendar systems: the Julian calendar and the Roman calendar. The Roman calendar was structured along the lines of the lunar cycle and was 304 days long—notably shorter than the Gregorian calendar used today, which has 365 days (and one extra day every leap year). The shorter Roman year consisted of 10 months and lasted from March to December; the period we now know today as January and February were not included in the official calendar because winter conditions meant many forms of work were not possible. 

Due to the different lengths of lunar and solar cycles, the people of the Roman Republic eventually found that the calendar was out of step with the natural year, and demand grew for a change. Julius Caesar confirmed the new calendar following his return to Rome in 46 BCE. The replacement—which followed a solar cycle of 365 days—was introduced in 45 BCE. It was named the Julian calendar after the Roman general.

Coligny Calendar

The fragments of this intriguing calendar were found in the Coligny area of eastern France in 1897. Dating revealed the pieces were made when France was part of what was then known as Roman Gaul in the 2nd or 3rd century CE. 

The bronze solar calendar featured 12 months—but some months contained only 29 days. The artifact also included more obscure features, such as cryptic Gaulish words describing certain days and mysterious crosses and bars. The calendar has become the subject of much scholarly research and interpretation in the years since its discovery.

Aztec Calendar

The Aztec civilization created two calendars to guide their world. One was a 365-day solar calendar; the other was a ritual calendar that contained 260 days. The solar calendar had the same number of days as the Julian calendar that was used in Europe in the same time period, but the Aztecs had a different method for subdividing the year. Their calendar used a system of 18 months containing 20 days each (the additional five days were added at the end of the year). 

The ritual calendar was comprised of two wheels. One showed numbers, and the other depicted signs with names; the two parts combined to create a unique code for each day. 

Aztec people were named for the day they were born—the names generated by the two wheels were even believed to determine their destiny.

Florentine Calendar

For many centuries between the fall of the Roman Empire and the unification of the country in 1871, Italy was actually made of a number of city-states that existed independently of each other. This is one of the reasons it was possible for a Florentine Calendar to exist separately from the Julian calendar that many other places had already adopted. 

The Florentine Calendar year began on March 25, which was celebrated as the date of the Annunciation of Mary and occurred nine months before Christmas. This continued to be the beginning of the calendar year in Florence long after other places began celebrating the New Year on January 1. 

When the Gregorian calendar was introduced in 1582, the Republic of Florence rebelled by continuing to use the Florentine calendar until a 1750 decree obliged them to change. The date of the Florentine New Year continues to be celebrated on March 25 as part of Florence’s customs to this day. 

French Republican Calendar

One of the many things that changed in France following the French Revolution was the calendar itself. France, alongside most other European nations, adopted the Gregorian calendar following the switch from the Julian calendar. But the massive changes the country experienced after the Revolution led to calls for a new system of measuring and dating time. 

And thus the French Republican calendar was created. As well as a new dating system that included weeks consisting of 10 days each, the calendar also used different names for the months and days, each of which was connected to nature (the month that stretched from what we would consider late May to mid-June, for instance, was known as Prairial after the French word for “meadow”). 

Napoleon abolished the French Republican Calendar and returned the country to the Gregorian calendar in 1805. In 1871, it was briefly revived by the government of the Paris Commune, who held power in the city from March to May that year. After the fall of the commune on May 28, Paris again returned to the Gregorian calendar, which it continues to use to this day.

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