Fasti Antiates, circa 67–55 B.C., painted plaster
Palazzo Massimo alle Terme, Museo Nazionale Romano
"The calendar of Republican Rome is represented by the fragmented Fasti Antiates Maiores. In the reconstruction above, the abbreviated names of the months are arranged across the top, preceded by the letter K (Kalends, the first day of the month). The Non (Nones) is indicated as the fifth day, and the Eidus (Ides) as the thirteenth. At the bottom are the total number of days in each month. (The intercalatory month of Intercalaris, which was included every other year, is represented by the thirteenth column.) The days themselves are listed vertically beneath each month and represented by a recurring cycle of letters A through H, every ninth day, counting inclusively, being identified as a market day, nundinae, which was painted in red (hence, a "red-letter day").
Besides these nundinal letters, the day had an additional letter (notae dierum) denoting its status: fasti (F), days on which civil and legal business could be conducted; nefasti (N), in which these activities were prohibited; and comitiales (C), when public assemblies (comitia) could convene and vote. Other letter designations identified days about which less is known. EN (endotercisi) identified those that were divided between the morning and evening, which were nefastus, and the afternoon, which was fastus. NP probably abbreviated nefastus publicus and designated public holidays. Large letters mark important state festivals and smaller letters, brief notations, such as the name of a divinity or ludi to note games held in honor of the gods.
There also were days, although not identified as such in the calendar, in which activity either was restricted in some way or avoided altogether as unlucky (dies atri), or--if following the Kalends, Nones, and Ides (dies postriduani)--inauspicious for any new undertaking (Varro, On the Latin Language, VI.29). Augustus, for example, "also had regard to certain days, refusing ever to begin a journey on the day after a market day, or to take up any important business on the Nones" (Suetonius, Life of Augustus, XCII).
In this detail [second image above] from the Fasti Antiates, one can see the festivals for the latter part of April. Painted directly on the fresh plaster in red and black on a white background, the fresco was found at the site of Nero's villa at Antium (Anzio). It is the oldest version of the fasti (indeed, only one other painted calendar exists) and a unique example of the lunar calendar of Numa Pompilus, which was followed until the solar calendar was instituted by Julius Caesar in 46 BC.Here, in red, one can see the celebration of the Cerialia (Cereri Libero) in honor of Ceres, the goddess of grain (April 19) and the Vinalia Priora (Veneri Erucinae) in celebration of Venus (April 23), when wine from the previous year's vintage could be sold. Between the two festivals there is the anniversary of Rome itself (Roma condita) on April 21, when the city traditionally was thought to have been founded in 753 BC. The only other historical date on the calendar is July 18 (Dies Alliensis), when Rome was defeated at the river Allia and its legions nearly destroyed by the Gauls in 390 BC (Varro, On the Latin Language, VI.32).
The Fasti Antiates is the only Roman calendar to date from the Republic. All others are from the time of Augustus and Tiberius, except for two later codex calendars from the fourth and fifth centuries AD. Altogether, more than forty calendars survive, some almost complete, others only in fragments. The largest is the Fasti Praenestini, which measured approximately six by eighteen feet."