Months of the Roman calendar

Mercedonius (Latin for "Work Month"), also known as Mercedinus, Interkalaris or Intercalaris (), was the intercalary month of the Roman calendar. The resulting leap year was either 377 or 378 days long. It theoretically occurred every two (or occasionally three) years, but was sometimes avoided or employed by the Roman pontiffs for political reasons regardless of the state of the solar year. Mercedonius was eliminated by Julius Caesar when he introduced the Julian calendar in 45 BC.

thumb|August panel from a Roman mosaic of the months (from El Djem, Tunisia, first half of 3rd century AD) Sextilis () or mensis Sextilis was the Latin name for what was originally the sixth month in the Roman calendar, when March (Martius, "Mars' month") was the first of ten months in the year. After the calendar reform that produced a twelve-month year, Sextilis became the eighth month, but retained its name. It was renamed Augustus (August) in 8 BC in honor of the first Roman emperor, Augustus. Sextilis followed Quinctilis, which was renamed Julius (July) after Julius Caesar, and prece

300px|thumb|July panel from a Roman mosaic of the months (from El Djem, Tunisia, first half of 3rd century AD)

first month of the ancient Roman year

thumb|May is represented by the veneration of Mercury (mythology)|Mercury on this panel from a [[Roman mosaic of the months (from El Djem, Tunisia, first half of 3rd century AD)]] Maius or mensis Maius (May) was the fifth month of the ancient Roman calendar in the classical period, following Aprilis (April) and preceding Iunius (June). On the oldest Roman calendar that had begun with March, it was the third of ten months in the year. May had 31 days.

thumb|April panel from a Roman mosaic of the months (from El Djem, [[Tunisia, first half of 3rd century AD)]]

thumb|upright=1.2|Drawing of the month of February (Mensis Februarius) based on the Calendar of Philocalus (354 AD), with a caption explaining that because the wandering [[Manes or souls of the dead can permeate the earth in this month, "the shades" (ghosts) are placated by commemorative honors]]

thumb|upright=1.5|Drawing of the fragmentary Fasti Antiates, a pre-Julian calendar showing Ianuarius (abbreviated IAN) at the top of the first column

month of the ancient Roman calendar