Mount Belles or Kerkinitis is located northeast of Lake Doirani and has approximately 60 km length and 7-9 km width. The highest point is at Radomir top (Radomir - Kalabak), at 2,029 meters, while the overall altitude varies between 300 and 1900 meters above sea level. The climate of the region has obvious Mediterranean characteristics. The region has been the battleground of Kleidi battle at 1014, which proved important for the fall of the First Bulgarian Empire, while it was the site of fighting during the German invasion to Greece in the Second World War.
Today 45% belongs to Greece, 35% to FYROM and 20% to Bulgaria.