Besides Havešová, Rožok, and Stužica (all of them located in Bukovské vrchy), there is a fourth component situated in Slovakia, named Kyjovský prales of Vihorlat.

In 2017, UNESCO extended the site, adding forests in Albania, Austria, Belgium, Bulgaria, Croatia, Italy, Romania, Slovenia, and Spain.

[4] In 2021 UNESCO extended the site again adding forests in Bosnia and Herzegovina, Czechia, France, Italy, North Macedonia, Poland, Slovakia and Switzerland.

[5] Then in 2023 further minor extensions were made, including an expansion to the Dürrenstein-Lassingtal site in Austria, and the addition of a forest at Paklenica National Park in Croatia.

[13][14][2] This is a transnational serial nature UNESCO World Heritage Site, encompassing 94 component parts (forests) in 18 European countries.