What are Julius Caesar's legacies to the modern world?

Julius Caesar ended temporarily the Roman Civil war that had raged for over a hundred years when he defeated General Pompeii. Julius' great nephew Octavian (Augustus) started the institution of Emperors via the Principe. Julius Caesar did give us what we know as the modern calendar with a leap year every forth year. His military achievements were awesome as he defeated the celts in Gaul that in 390bc sacked Rome but Julius as Governor of Gaul and General of the Roman forces there defeated the last of the celtic tribes led by Vercingetorix.