Niš Fortress was built by the Turks between 1719 and 1723 to protect the road to Istanbul. It is one of the best preserved Turkish fortresses in the Balkans. Note the remarkably well-preserved Istanbul Gate, one of the city's symbols. Inside the enclosure there is a 15C hammam, the Ottoman arsenal, the 16C Bali-beg Mosque, the Eastern-style royal palace and the archaeological site that reveals the remains of the Roman and Byzantine periods.