Fort St. Ivana, i.e. Fort / Twierdza św. Jana is a 17th-century defensive structure, located on a hill (115 m above sea level) north of the old part of Šibenik. It owes its name to the medieval church of St. John the Baptist, who was here from the first half 15th century The fortress was built in 1646 and in the same year fought off the first assault.
Construction of the fortress of St. Jana lasted only 58 days. Father Antonio Leni, a Genoese engineer in the Venetian service, in the spring of 1646 designed a simple fort with elongated front horns (the so-called tenaille, or pliers) and two bastions. Construction, supported by all city residents, began on August 1, in September the fortress was ready, and in October repelled the first Turkish attack. In the next 25,000 Ottoman soldiers besieged the fortress for a month and did not manage to conquer it.
St. fortress John was the most modern and strongest fortification of Šibenik at the time of its creation. Despite falling into ruin, the fortress retained its original form.