thus a cycle, at the end of which, the beginning of the ancient year nearly coincided with that of the solar year. As the coincidence, however, was not perfect, a month of 24 days was interposed in every eleventh lūstrum. It is highly probable that the recurrence of such a cycle or great year was, from the earliest times, solemnized with sacrifices and purifications, and that King Servius did not introduce them, but merely connected them with his census, and thus set the example for subsequent ages, which however, as we have seen, was not observed with regularity. The last lūstrum was solemnized at Rome, in AD 74, in the reign of Vespasian. See also Lustratio Decade Century Millennium References External links Livius.org Lustrum Society of ancient Rome Population Units of time Quinquennial events