The ludi were not holidays (feriae), as such, although they did have their origins in religion and ritual, and the days of their celebration were considered dies festi. The oldest and most famous of the public games were the Ludi Romani (Roman Games), which originally were vowed in honor of Jupiter Optimus Maximus, whose temple was dedicated on September 13, 509 BC, as a votive offering if victory were won in battle. They were celebrated in the Circus Maximus following the triumphal procession (pompa) from the Temple of Jupiter on the Capitol. By 366 BC, they had become an annual event, no longer associated with the triumph, and were held for several weeks in September.
These were the only public games until the Ludi Plebei (Plebeian Games) were established c.220 BC to bolster public morale during the Second Punic War with Hannibal, as were the Ludi Apollinares c.212 BC and the Ludi Megalenses in 204 BC. Additional games included the Ludi Ceriales, consecrated to Ceres in 202 BC, and the Floralia, restored in 173 BC. By the time of the late Republic, more than half the days in April were devoted to the games. New ones also were decreed, including the Ludi Victoriae Sullae, which celebrated the victory of Sulla at the Colline Gate in 82 BC, and the Ludi Veneris Genetricis to mark the victory of Caesar at Pharsalus in 48 BC.
These and other games came to occupy an increasing number of days on the calendar and originally were devoted either to chariot racing (ludi circenses), animal hunts (venationes), or theatrical performances (ludi scaenici). Later, by the end of the Republic, gladiatorial contests (munera) were included. With the advent of the emperors, additional festival days and public games were declared, celebrating the emperor's birthday, day of accession, notable victories, possible consecration, and even fortuitous escapes from assassination. The result was such a profusion of holidays (perhaps as much as half the calendar year) that Romans spent much of their time at the Circus.
Of all the games, the most intriguing are the Ludi Saeculares (Secular Games). Valerius Maximus (II.4.5) relates the story of a father whose three children were sick with the plague. Directed by an oracle to drink water warmed from the altar of Dis and Proserpina, they landed at Tarentum, at the western boundary of the Campus Martius, where the presence of hot springs led to the belief that it was an entrance to the underworld. The children were cured and the grateful father celebrated with sacrifices, games, and a lectisternium, in which couches were set as if the gods were in attendance, for three successive nights, one for each child.
In fact, the origin of these early Ludi Tarentini is obscure and their celebration, as Censorinus complains (XVII), uncertain. The first historical games probably were in 249 BC and a century later in 146 BC (Zosimus, II.5) at times of national calamity (the First and Third Punic wars).
Customarily celebrated only once in a lifetime, the saeculum was defined in the Republican period as one hundred years, the longest span of human life. Expiatory sacrifices were offered then to the deities of the underworld to mark the commencement of a new generation. By the time of Augustus, the period was fixed at one hundred ten years. Whatever the length, the Secular Games more often were scheduled for political reasons than to denote a particular cycle of time. Augustus celebrated them in 17 BC to inaugurate the beginning of a new age, commissioning Horace to write a choral hymn, the Carmen Saeculare (in which the seven hills of Rome are first mentioned). Claudius found a pretext for the games in AD 47 to mark the eight-hundredth birthday of Rome; Domitian held them again in AD 88 (counting almost a century since Augustus), and Severus in AD 204 (two saecula after those of Augustus). Magnificent games were celebrated by Philippus (Philip the Arab) for the last time in AD 248 on the thousandth anniversary of Rome's founding (following Claudius' precedent of a one-hundred year saeculum) (Victor, XXVIII; Eutropius, IX.3; Orosius, VII.20).
Zosimus, whose Historia Nova was written in the late fifth century AD, provides the most complete description of the Ludi Saeculares.
"Heralds go about summoning everyone to attend a spectacle they have never seen bfore and will never see again. In summer, a few days before it begins, the Quindecemviri sit in the Capitol and in the Palatine temple on a tribunal and distribute purifying agents, such as torches, brimstone and pitch, to the people; slaves do not participate in this, only freemen. When all the people assemble in the above-mentioned places and in the temple of Diana on the Aventine, each one bringing wheat, barley and beans, they keep the all-night vigils to the Fates with great solemnity for [lacuna] nights. Then when the time arrives for the festival, which is celebrated for three days and three nights in the Campus Martius, the victims are dedicated on the bank of the Tiber at Tarentum" (II.5.1-2).
He goes on to describe the ceremony. The first night the emperor participated in the sacrifice of three lambs by the Tiber. Fires were kindled, a newly composed hymn sung, and sacred pageants presented. The next day, there were sacrifices at the Capitoline and games dedicated to Apollo and Diana. On the second day, noble matrons prayed and sang hymns to Juno. On the third, twenty-seven boys and the same number of girls, whose parents both still were living, sang hymns in the Temple of Apollo for the preservation of Rome. During this time, games were celebrated in the circus and theaters.
"Therefore, as the [Sibylline] oracle truly says, while all this was observed according to direction, the Roman empire was safe and Rome remained in control of virtually all the inhabited world, but once this festival was neglected after Diocletian's abdication, the empire gradually collapsed and was imperceptibly barbarised.... From the consulship of Chilo and Libo [AD 204], when Severus celebrated the Secular Games, until Diocletian for the ninth time and Maximian for the eighth were consuls [AD 304], one hundred years elapsed. Maximian wanted to celebrate the festival then, contrary to rule, but next year Diocletian became a private citizen instead of emperor and Maximian followed his example. When Constantine and Licinius were in their third consulship [AD 314], the period of one hundred and ten years had elapsed and they ought to have kept up the traditional festival. By neglecting it, matters were bound to come to their present unhappy state" (II.7.1-2).
So Zosimus, the last pagan historian, attributed Rome's decline.
Reference: Varlerius Maximus: Memorial Doings and Sayings (2000) translated by D. R. Shackleton Bailey (Loeb Classical Library); Zosimus: New History (1982) translated by Ronald T. Ridley.