abstract:Pope Gregory XIII (; 7 January 1502 – 10 April 1585), born Ugo Boncompagni, was the head of the Catholic Church from 13 May 1572 to his death in 1585. He is best known for commissioning and being the namesake for the Gregorian calendar, which remains the internationally accepted civil calendar to this date.
The solar calendar in usethroughout mostof the world, sponsored byPopeGregoryXIIIin 1582 as a correctedversion of the Juliancalendar. See table at calendar.
The so-called Meridian Hall, created to verify the accuracy of the calendar PopeGregoryXIII promulgated in 1582, is in the Vatican Secret Archives, which hold some 10m documents stored by the papacy over the past 1, 200 years.
Before the Revolution, Russia had not yet adopted the Gregorian calendar, introduced by PopeGregoryXIII in 1582 to mitigate the errors of the Julian calendar, which owes its name to the Roman emperor who had chosen it 46 years before the birth of Jesus Christ.