The Skopje Fortress commonly referred to as Kale Fortress, or simply Kale (from kale, the Turkish word for 'fortress'), is a historic fortress located in Skopje, the capital of the Republic of Macedonia. It is situated on the highest point in the city overlooking the Vardar River. The fortress is depicted on the coat of arms of Skopje, which in turn is incorporated in the city's flag. The first fortress, according to research and available data, is believed to have been built amidst the 6th century A.D., on land that had been inhabited during the Neolithic and Bronze ages or roughly 4000 B.C. It was constructed with yellow limestone and travertine and along with fragments of Latin inscriptions, asserts the idea that the fortress originated from the Roman city of Skupi, which was completely destroyed by an earthquake in 518. The fortress is thought to have been reconstructed during the rule of emperor Justinian I and constructed further during the 10th and 11th centuries over the remains of emperor Justinian's Byzantine fortress which may have been destroyed due to a number of wars and battles in the region, such as that of the uprising of the Bulgarian Empire against the Byzantine Empire under the rule of Peter Delyan. Not much is known about the Medieval fortress apart from a few documents which outline minor characteristics in the fortress' appearance. http://www.exploringmacedonia.com/fortress-kale.nspx