The Rila Mountains contain Musala Peak - at 2,925 metres, it is the highest point in Bulgaria and in the entire Balkan Peninsula. The name Musala means 'close to God' in an old language, because the peak sits so high it is often in the clouds. From the top on a clear day you can see four countries.
In the Pirin Mountains there are more than 200 glacier lakes, each carved out by ice during the last Ice Age. These lakes have names like the Scary Lake, the Fish Lake and the Tear Lake. The water is so clear and cold that it looks almost blue-green, reflecting the rocky peaks above.
Both ranges are UNESCO Biosphere Reserves, which means they are protected wild spaces. Brown bears, chamois (a kind of mountain goat), golden eagles and Balkan chamois all live in these mountains. There are also ancient Bosnian pine trees in the Pirin that are more than 1,000 years old - they were saplings when Rila Monastery was being built.
In winter the mountains fill with skiers and snowboarders from all over Europe. In summer, hiking trails wind through meadows full of wildflowers, past waterfalls and up to ridges where you can see for hundreds of kilometres. Shepherds still move their flocks of sheep up into the high meadows each summer, just as they have for thousands of years.