Klis is considered one of the most important fortress in Croatia . It is situated on a steep cliff which provides a view of the city of Split, Solin , islands , Hvar , Vis and Solta . Nearby is situated a cave Vranjaca , which is often called the pearl of the Dalmatian underworld . In the past Klis was the center of the famous family Trpimirovići . From this time are visible the traces of Croatian heritage , mostly from the reign of Prince Trpimir , and thus this city was first mentioned in documents from 852. The villagers are engaged in agriculture , ie vegetable growing and producing of healthy food , especially known for the production of virgin olive oil . Klis is known for its cake ujenak that is made of delicious fruits . It is made from almonds and walnuts , which are mixed with dried grapes . The particularity of this cake is a large amount of homemade olive oil and the sweetness of the honey and sugar which are put on the upper side of the dough. Salted fish , salted olives,... well known Uskočka herb brandy and roast lamb on a spit also have to be tried out. Locals believe that the future of Klis lies in food production, rural tourism and old crafts. Interesting information is that young people of Klis live just out of the money they get from their parents, and most they get from their mothers who earns money by selling vegetables at the market in Sinj or Split. Most writers say the fortress Klis is very inaccessible area located between Kozjak and Mosor. Well known are Klis valleys which are specific for its mountain saddle configuration. Also worth mentioning is archaeological research in which they found the remains of Illyrian at Klis. It is known that the Illyrians lived on a Klis field, but also that they had an important role in the ancient world. Klis fortress can be visited by people of all ages, tourists, it is especially popular for school excursions and scientists.