Complex sentence: Year 499 BC was a year of the pre-Julian Roman calendar.In the Roman Empire it was known as the Year of the Consulship of Aebutius and Cicurinus (or, less frequently, year 255 "Ab urbe condita").
Split into simpler sentences: Year 499 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Aebutius and Cicurinus (or, less frequently, year 255 "Ab urbe condita").