The Holy Mountain

On an isolated peninsula jutting into the Aegean Sea, a group of monastaries cling to the steep and heavily forested mountainsides, maintaining an existence semi-autonomous from Greece. Just over two thousand monks and laymen live on the peninsula, with no women or children (or non-Orthodox men) allowed to reside.

It's official name is the Autonomous Monastic State of the Holy Mountain, but it is commonly referred to as Mount Athos.

Civil authorities are appointed by the Greek Ministry of Foreign Affairs, but spiritually, Mount Athos is under the jurisdiction of the Ecumenical Patriarch in İstanbul. The patriarch is the Orthodox version of the Catholic pope, with the qualifications of being a Turkish citizen of Greek ethnicity.

To visit the peninsula, one must take a ferry. "Before embarking on the boat all visitors must have been issued a diamonitirion, a form of Byzantine visa that is written in Greek, dated to the Julian calendar, and signed by four of the secretaries of leading monasteries." Or so says Wikipedia.