Pliva is a relatively small river in central parts of Bosnia and Herzegovina, however one of the most significant in terms of natural, cultural and historical heritage and value as a natural rarity. For hundreds of years this region was the ultimate stronghold of the Bosnian Kingdom, with town of Jajce as permanent seat of the last kings of Bosnian Kingdom. The entire region of Jajce is rich in natural heritage that cannot be viewed in isolation from the built heritage. In Jajce, these two components are closely intermingled. Plivska lakes At the village of Jezero the Pliva flows into the larger of two lakes, Veliko Plivsko Lake (veliko meaning large), then into two smaller Malo Plivsko Lake (malo meaning small) and Okruglo Lake (okruglo meaning round). Both of the Pliva lakes lie in a basin of karstic rock, mainly dolomite and limestone, which has given rise to their most distinctive feature, same as nearby Una River in Bosnia and Herzegovina and Plitvice Lakes in Croatia. The lakes are separated by natural dams of travertine, which is deposited by the action of moss, algae and bacteria. The encrusted plants and bacteria accumulate on top of each other, forming travertine barriers which grow at the rate of about 1 cm per year.