Convert between calendar dates and the Roman form (Kalends, Nones, Ides)
Popes: full list, St. Peter (AD 33) to the present; dates before that show n/a. Exact days are used where the historical record gives them; between Lando (913) and Pius V (1572) only years are reliably attested, so those show year precision (a handful of same-year successions, e.g. 1276 or 1045, can't be told apart at that resolution). Consules: the ordinary (eponymous) consuls for each year, 509 BC–AD 541, only — suffect consuls are omitted. Mechanically extracted from Wikipedia's List of Roman consuls (itself mainly Broughton's Magistrates of the Roman Republic); early Republic names are the traditional Fasti and are themselves disputed by modern scholarship, and about 30 years have no consul attested at all and show n/a.