The Monastery of Saint Ivan of Rila, better known as the Rila Monastery (Bulgarian: Рилски манастир, Rilski manastir) is the largest and most famous Eastern Orthodox monastery in Bulgaria. It is situated in the southwestern Rila Mountains, 117 km (73 mi) south of the capital Sofia in the deep valley of the Rilska River at an elevation of 1,147 m (3,763 ft) above sea level. The monastery is named after its founder, the hermit Ivan of Rila (876 - 946 AD).

Founded in the 10th century, the Rila Monastery is regarded as one of Bulgaria's most important cultural, historical and architectural monuments and is a key tourist attraction for both Bulgaria and Southern Europe. In 2008 alone, it attracted 900,000 visitors. The monastery is depicted on the reverse of the 1 lev banknote, issued in 1999.

It is traditionally thought that the monastery was founded by the hermit St. Ivan of Rila, whose name it bears, during the rule of Tsar Peter I (927-968). The hermit actually lived in a cave without any material possessions not far from the monastery's location, while the complex was built by his students, who came to the mountains to receive their education.

Rila (Bulgarian: Рила, pronounced [ˈriɫɐ]) is a mountain range in southwestern Bulgaria and the highest mountain range of Bulgaria and the Balkans, with its highest peak being Musala at 2,925 m. The massif is also the sixth highest mountain in Europe (when each mountain is represented by its highest peak only), coming after the Caucasus, the Alps, Sierra Nevada, the Pyrenees and Mount Etna, and the highest between the Alps and the Caucasus. The larger part of the mountain is occupied by the Rila National Park.

The name Rila is believed to be of Thracian origin and is thought to mean "well-watered mountain", owing to Rila's abundance of glacial lakes (about 200) and hot springs in fault areas at the base of the mountain. Some of the Balkans' longest and deepest rivers originate from Rila, including the Maritsa, the Iskar and the Mesta.

Culturally, Rila is famous for the Rila Monastery, Bulgaria's largest and most important monastery founded in the 10th century by Saint John of Rila.

Rila is a dome-shaped horst mountain, part of the Balkans' oldest land, the Macedono-Thracian Massif. It was formed by granite and gneiss rocks and crystal schists during the Paleozoic (250,000,000 years ago). Rila's alpine relief was formed during the Pleistocene by a series of glacial periods. During the most recent, so-called Würm glaciation, 10-12,000 years ago the permanent snow line was at 2,100 m above sea level. Above this line glaciers radically changed the existing relief, carving out deep cirques, sharp pyramid-shaped peaks, rock pinnacles, various valleys, moraines and other typical glacial formations.