Mind-Benders of Greek & Roman History
The longest year in history had 445 days
By 46 BCE the Roman calendar had drifted so far out of step with the seasons that Julius Caesar, advised by the Alexandrian astronomer Sosigenes, inserted extra months to force it back into line. That single year ran fifteen months and about 445 days — later nicknamed the “year of confusion” — before his new sun-based calendar took effect the following year.
How we know
The year 46 BCE was extended to about 445 days across 15 months by inserting intercalary months, on the advice of Sosigenes of Alexandria; the reformed Julian calendar began 1 January 45 BCE. Attested by Suetonius, Macrobius, and Censorinus.
One of many fact-checked wonders across eight traditions at The Spring of Wisdom.