The exceptionally well-preserved fortress Knin belongs to one of the largest defensive structures in Croatia and is the second largest military facility in Europe. It lies on the top of the steep Spas Mountain, just 100 meters above the city of Knin. Inside there is a museum presenting treasures found during archaeological excavations carried out here, as well as clothing and weapons from ancient times. There is also a restaurant in the fortress.
The construction of the fortress began in the ninth century. Its greatest development occurred during the reign of Demetrius Zvonimir, king of Croatia from 1076. It was then the political center of the kingdom. Over the centuries, the fort was expanded, which is why today it impresses with its impressive size. It is 470 meters long, 110 meters wide (at its widest point) and is divided into five parts: Donji Grad, Sredniji Grad, Gornji Grad, Kastel Knin and Juzni Grad.