The modern calendar is an extraordinary device which establishes dates of various periodic events such as eclipses, historical events, and religious festivals. It also measures equal intervals of time for commercial, statistical and scientific purposes. Many ancient civilizations, including the Aztecs had quite sophisticated calendars. However, the history of our calendar can be traced back to the Egyptians who around 4241 BC devised a calendar of 12 months of 30 days each, plus five additional days.
