Durmitor is also an important biodiversity spot.[2] Following the inscription to the UNESCO World Heritage List in 1980, the borders of the site were modified in 2005 to be in line with the national park boundaries.[10] Stećci Medieval Tombstones Graveyards* Žabljak, Plužine 2016 1504; iii, vi (cultural) Stećci (sing. stećak) or the medieval tombstones are the monolith stone monuments found in the regions of the present Bosnia and Herzegovina, parts of Croatia, Serbia, and Montenegro. They first appeared in the 12th century and reached their peak in the 14th and 15th century.