Ledenika (Леденика) is a cave in the Northwestern parts of the Balkan Mountains, 16 km away from the Bulgarian city of Vratsa, its entrance being at 830m above sea level. It features an abundance of galleries and impressive karst formations including stalactites and stalagmites, dating back a thousand years. The cave is about 300m long and contains ten separate halls. The biggest one is the Concert Hall. The way to it is through the Passage of Sinners. Only those whose heart is pure can pass through it [Citation Needed]. Once the cave was full of water but now only a small lake has remained - the Lake of Wishes. The legend says that if you dip your hand in the ice-cold water of the lake and make a wish, the wish will come true.