Sliven

Zmeevi dupki is the largest and most remarkable cave with a length of 150 m, 1 ha area, located about four kilometers east of Sliven in the gorge of Maara dere / Zmeevo River.

It stretches towards the north-south, its northern part is deeper by about 1.5 m from the south in the northern edge several branches with stalactites causing delight in everyone they saw the "church", "Roman tomb," Bishop throne.