Mount Athos is a mountain on the Athos peninsula in northeastern Greece. It is an important center of Eastern Orthodox monasticism. The mountain and most of the Athos peninsula are governed as an autonomous region in Greece by the monastic community of Mount Athos, which is ecclesiastically under the direct jurisdiction of the Ecumenical Patriarch of Constantinople. The remainder of the peninsula forms part of the Aristotelis municipality. Women are prohibited from entering the area governed by the monastic community by Greek law and by religious tradition.

Eastern Orthodoxy, otherwise known as Eastern Orthodox Christianity or Byzantine Christianity, is one of the three main branches of Chalcedonian Christianity, alongside Roman Catholicism and Protestantism. Like the Pentarchy of the first millennium, the mainstream Eastern Orthodox Church is organised into autocephalous churches independent from each other. In the 21st century, the number of mainstream autocephalous churches is seventeen; there also exist autocephalous churches unrecognized by those mainstream ones. Autocephalous churches choose their own primate. Autocephalous churches can have jurisdiction (authority) over other churches, some of which have the status of "autonomous" which means they have more autonomy than simple eparchies.