The Megalesia, Megalensia, or Megalenses Ludi, was a festival celebrated in Ancient Rome from April 4 to April 10, in honour of Cybele, known to Romans as Magna Mater (Great Mother). The name of the festival derives from Greek Megale (μϵγάλη), meaning "Great". Ludi were the games or entertainments associated with religious festivals.
Cybele's cult image was brought to Rome from Pessinus in 204 BC, along with the goddesses Galli priests. As the "Great Mother of the Gods" and a purported ancestral Trojan goddess of Rome's ruling patrician caste, she was recruited to act on Rome's behalf in the war against Carthage. Her arrival was solemnized with a magnificent procession, sacred feasts (lectisternia), games, and offerings to her at the temple of Victory on the Palatine Hill, where her image was temporarily housed. In 203 Cybele was promised a temple of her own. Games in her honour were celebrated in 193. Regular annual celebration of the Megalesia began in 191, with the temple's completion and dedication by Marcus Junius Brutus
The Megalesia commenced on April 4, the anniversary of Cybele's arrival in Rome. The festival structure is unclear, but it included ludi scaenici (plays and other entertainments based on religious themes), probably performed on the deeply stepped approach to her temple; some of the plays were commissioned from well-known playwrights. On April 10, her image was taken in public procession to the Circus Maximus, and chariot races were held there in her honour. The racetrack could be seen from her temple's threshold, and a statue of Magna Mater was permanently sited on the racetrack's dividing barrier, showing the goddess seated on a lion's back: the goddess could thus watch the festivities held in her honour.
Roman bystanders seem to have perceived Megalesia as either characteristically "Greek"; or Phrygian. At the cusp of Rome's transition to Empire, the Greek Dionysius of Halicarnassus describes this procession as wild Phrygian "mummery" and "fabulous clap-trap", in contrast to the Megalesian sacrifices and games, carried out in what he admires as a dignified "traditional Roman" manner; Dionysius also applauds the wisdom of Roman religious law, which forbids the participation of any Roman citizen in the procession, and in the goddess's mysteries; Slaves are forbidden to witness any of this. In the late republican era, Lucretius vividly describes the procession's armed "war dancers" in their three-plumed helmets, clashing their shields together, bronze on bronze, "delighted by blood"; yellow-robed, long-haired, perfumed Galli waving their knives, wild music of thrumming tympanons and shrill flutes. Along the route, rose petals are scattered, and clouds of incense arise. The goddess's image, wearing the Mural Crown and seated within a sculpted, lion-drawn chariot, is carried high on a bier. The Roman display of Cybele's Megalesia procession as an exotic, privileged public pageant offers signal contrast to what is known of the private, socially inclusive Phrygian-Greek mysteries on which it was based.