Fort Nečven is a medieval Croatian fortress from the 14th century, and one of the most important fortified buildings in Croatia in terms of size and degree of preservation.
The fort and its associated yard cover a square kilometer. It used to be surrounded by high walls made of small, poorly assembled stones combined with lime. The northeast courtyard wall was separated by a deep moat and perhaps a moving (lifting) bridge from the remains of the fortress. The walls were over a meter thick. The steep southern walls reached a height of up to 15 metres and consisted of five floors. The northern side, where the five-storey ancient square tower stands, is now filled with rubble.
On the other side of Krka, opposite from Nečven, are remnants of another old Croatian city, Trošenj (Čučevo). Those cities were previously connected by a bridge (which was destroyed in 1647 during the war between Don Stjepan Sorić and Krajišnici) that connected central Dalmatia with Bukovica and Ravni Kotari. The bridge was supervised and travellers who passed the border between Šubić's and Nelipić's properties were charged a toll.
The First Lords of Nečven-Nelipić were at the height of their power after the collapse of Mladen Šubić II (1322 AD) when they were named as the major force in the Southern Croatian region by Prince Nelipac.
The Turks ruled Nečven from 1522 to 1678 or 1686, apart from a period between 1648 and 1670 during which it was given to Venetian vassals Šibenik and Trogir, and burned down at the orders of Leonardo Foscolo, using the established constructions they found and the mighty wooden bridge over the river Krka. In their time there lived: the Dizdars, the Aghas, the Begs and the Kadijas), which showed a great deal how important the fort and the city was because it was in effect the seat for administrative and judicial power in that area for that time.
By the end of the 18th century, the fortress lost its strategic importance, and it was abandoned and the surrounding villages depopulated.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.