Slovenias grandest natural miracles the countrys most visited site and one of the most fascinating castles postojna cave is the most prominent of slovenias sights and paradise for explorers of natures miracles a system of 24 kilometers that river pivka created throughout the history has been first described in the 17th century but it has been a home to proteus anguinus for thousands of years lake cerknica is another miracle of karst region that you shouldnt miss now you see it now