dating and the irregularity of Roman intercalation means that dates which can be independently verified are invariably weeks to months outside of their "proper" place. Two astronomical events dated by Livy show the calendar 4 months out of alignment with the Julian date in 190BC and 2 months out of alignment in 168BC. Thus, "the year of the consulship of Publius Cornelius Scipio Africanus and Publius Licinius Crassus" (usually given as "205BC") actually began on 15March 205BC and ended on 14March 204BC according to the Roman calendar but may have begun as early as November or December 206BC owing to its misalignment. Even following the establishment of the Julian calendar, the leap years were not applied correctly by the Roman priests, meaning dates are a few days out of their "proper" place until a few decades into Augustus's reign. Given the paucity of records regarding the state of the calendar and its intercalation, historians have reconstructed the correspondence of Roman dates to their Julian and Gregorian equivalents from disparate sources. There are detailed accounts of the decades leading up to the Julian reform, particularly the speeches and letters of Cicero, which permit an established chronology back to about 58BC. The nundinal cycle and a few known synchronisms—e.g., a Roman date in terms of the Attic calendar and Olympiad—are used to generate contested chronologies back to the start of the First Punic War in 264BC. Beyond that, dates are roughly known based on clues such as the dates of harvests and seasonal religious festivals. See also List of calendars Julian, Alexandrian, Byzantine, & Gregorian calendars List of Roman consuls and ab urbe condita dating General Roman Calendar of the Catholic Church Roman festivals Undecimber Notes References Citations Bibliography . . . . . . . . & . . . . . . . . . . . . . . . External links Chris Bennett's reconstruction of early Roman dates in terms of the Julian calendar Early Roman Calendar – History James Grout: The Roman Calendar, part of the Encyclopædia Romana Roman Date Calculator The North American Institute of Living Latin Studies Calendars Calendar Time in Italy