St. Nicholas Fortress - Šibenik, Croatia

The formerly impenetrable St. Nicholas Fortress was built by the Venetians in the 16th century to defend against Turkish attacks. With a triangular shape and 32 cannons, the fortress was truly formidable. Its appearance alone was enough to keep away attackers. It was maintained by the military up until 1979, but now is abandoned and only seen by urban explorers and is surprisingly well-preserved. There is a footpath leading to the fortress from Sv. Nikola beach, or it can be accessed by boat.