The Russians became acquainted with the Christian religion in 860 A.D. In the middle of the 10th Century, Princess Olga of Kiev visited Constantinople and was baptized under the name Elene. Later, when her grandson Vladimir became a Christian, all the Russians became Christians too. Moreover, the Russians adopted the Cyrillic alphabet and the Julian calendar. In 1918 the government replaced the Julian calendar with the Gregorian one. However, the Russian Orthodox Church never accepted the Gregorian or the New Rectified Julian calendar. Even today it retains the old Julian calendar. An important but short-lived change in the history of the Russian calendar took place in the year 1929. Then the seven-day week was abolished being substituted with five-day intervals. This attempt was unsuccessful and finally the Soviet government restored the use of the initial Gregorian calendar and the ancient seven-day week.