In 1517, in accordance with approval from 1478, noblemen and landowners from Split brothers Jerolim and Nikola Cambi, built a castle on a islet to protect themselves and residents of Lažan and Kruševik settlements. The castle was cylindrically shaped (only one in Kaštela) and very suitable for defense.
North of Kruševik in the Lažana region the medieval church of St. Mihovil was built on the slope of Kozjak of the same name.
In the area of Kaštel Kambelovac castles of Grissogono i Lipeo families have been built. Peasants from an old Croatian village Kruševik built two castles, Velika and Mala Piškera. It was the only example where peasants have built their fortresses. Due to the large number of castles Kaštel Kambelovac developed in a stretched village.
On the slopes of Kozjak is a little church of St. Martin od Kruševika, former center of the Kruševik village. Today this church is known as Gospe na Krugu or Gospe od Snijega.
There is a guard house from the 16th century on the western side of the slope and a fortress Kaštilica near the summit of the mountain. Marked paths lead to these churches and mountain houses under Koludar (325 m) and Orlovo gnijezdo. Farther uphill and to the northeast mountaineers would exit to the ridge of Kozjak over slick vertical cliff secured by a steel rope. From there the path leads to Veliki vrj (780 m), the highest point of Kozjak. The upper part of the path is only for experienced mountaineers.