Final answer:
Julius Caesar's accomplishment was the establishment of a calendar that is still in use today, known as the Julian Calendar.
Step-by-step explanation:
One of the accomplishments of Julius Caesar was the establishment of a calendar that is still in use today, known as the Julian Calendar.
Caesar introduced this new calendar in 46 BC, which included the same 12 months as the calendar used today. He added a leap day at the end of February every 4th year and renamed the 5th month of the Roman year as July, in honor of himself.
This calendar played a crucial role in organizing time and has had a lasting impact on how we measure and mark the passing of years.