Year 800 (DCCC) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events By Place Europe September 15 - Oldest known mention of Castile. December 25 - Charles the Great's crowned emperor by Pope Leo III in Rome, marking the start of the Holy Roman Empire. Celtic monks begin work on the Book of Kells on the Island of Iona. The town of Shrewsbury, England's founded. Africa Bantu-speaking people settle in present-day Zambia (approximate date… (More on 800)