Nis is located in Southern Serbia and it is the administrative center of Nisava District. City is named after the Nisava River which flows through the city. Nis is the third largest city in Serbia with a population of 255.518. Nis is an important transportation hub with road and rail routes for Serbia and considered as the gateway of East and West. It is one of the oldest cities in Europe. It was founded by Celts around 3rd century BC.City is also an important historical place with landmarks such as Nis Fortress, Nisava Tower and the Skull Tower. Nis is also an important cultural city for Serbia with various museums, universities and the Nisville Jazz Festival. Nis is a member of the B40 Balkan Cities Network.