Here was faught The Battle of Kajmakchalan which was a battle between Serbian and Bulgarian soldiers on the Macedonian Front during World War I. There is a small church on the peak of Prophet Ilia where the skulls of dead Serbian soldiers are stored. You can see it from here.
You can read something more about it:http://en.wikipedia.org/wiki/Battle_of_Kajmakchalan
There will be more photos of this incredible weekend on Kajmakcalan
Can you see that little pick on the top of that mountain: http://sta.sh/02dn0ba3pv9m :)