Holy Monastery of Chilandariou

It was built in 1197 AD by Saint Sava, heir to the Serbian throne and Archbishop of Serbia. Saint Sava's father, when he abdicated the throne, came to Mount Athos and became a monk.
 
Today the monastery is the capital of Serbian orthodoxy, hosts more than 20,000 books, has about 75 monks and celebrates December 4 (Julian Calendar - Feast of the Presentation of the Virgin Mary).