Ever thought why February is the shortest month with only 28 days? The answer lies in the history of Roman Empire.
Before 713 BC the Roman calendar consisted of only 10 months, the winters were ignored and had no name because they considered it worthless as their live depended on agriculture. These 10 months were as follows:
Martius: 31 days
Aprilius: 30 days
Maius: 31 days
Junius: 30 days
Quintilis: 31 days
Sextilis: 30 days
September: 30 days
October: 31 days
November: 30 days
December: 30 days
After Numa become King he decided to change the calendar adding two more months to complete the days and make it a 12 month calendar like the lunar calendar which had 355 days. They added Ianuarius of 29 days and Februarius of 28 days.
This was because Romans considered even numbers to be unlucky so they made each month odd, so at last the February had to be an even number and become a 28 days month.