Rila
The most recognisable landmark of the mountain range is the Rila Monastery , Bulgaria's largest and most important monastery , founded in the 10th century by Saint John of Rila . Due to its outstanding cultural and spiritual value it was declared a UNESCO World Heritage Site in 1983 . Rila is also a popular destination for hiking , winter sports and spa tourism , hosting the nation's oldest ski resort Borovets , as well as numerous hiking trails . 
<triplet> Rila Monastery <subj> John of Rila <obj> founded by <subj> Rila <obj> located on terrain feature <triplet> World Heritage Site <subj> UNESCO <obj> maintained by