Essentially, a year during which the Pope grants a special indulgence, called the Jubilee, to all the faithful who visit Rome and pray according to specified conditions. First instituted in 1300 by Pope Boniface VIII, whose original intention was that it be celebrated only every hundred years. Since then there have been three changes in the intervals. In 1343, Pope Clement VI decreed that the Holy Year be celebrated every fifty years; Urban VI in 1389 reduced it to thirty-three years in honor of the years of Christ's life; and paul II in 1470 made it every twenty-five years, which is the period that has been kept every since. Pope Pius XI made an exception in 1933 to commemorate the nineteenth centennial of Christ's death, resurrection, and ascension. Since 1500 the Jubilee Indulgence could be gained in one's native country, under specified conditions, after the Roman year was completed. The opening and closing of the Holy Doors at St. Peter's in Rome marks the opening and closing of each Holy Year.