I recommend you do this walk in autumn - early or late October. That way you'll catch the area at its most colorful.
96,9 км (60,2 ми)
2 ч 18 мин
Keeping in mind the road from Sofia, I have made the program so that it is not difficult for you and you can see something on the way.
53,6 км (33,3 ми)
1 ч 13 мин
43,2 км (26,9 ми)
1 ч 4 мин