Across the world, Orthodox Christians mark Christmas with prayers, Mass

Across the world, Orthodox Christians are celebrating Christmas with Mass and prayers.

In Russia, both Prime Minister Dmitry Medvedev and President Vladimir Putin attended Christmas morning Mass early Wednesday.

At the Church of the Nativity, built over the West Bank grotto that Christians believe is the site of Jesus' birth, Palestinian President Mahmoud Abbas attended Mass early Wednesday as well.

In Egypt, Coptic Christians celebrated on Tuesday night with Mass on Christmas Eve. Egyptian President Abdel-Fattah el-Sissi attended one such Mass, escorted by Coptic Pope Tawadros II.

Orthodox Christians celebrate Christmas on Jan. 7, in accordance with the Julian calendar. This was largely replaced in western Europe by the Gregorian calendar 500 years ago.