Probably the main sight in Nis, is the fortress (Tvrdava). The current fortifications are of Turkish origin and were built in the early 18th century, although the history of a fortress on this site dates back to Roman times.
The rampart walls are more than 2 km long and include four gates, with the Istanbul Gate (Stambol kapija) being the best preserved.
The Istanbul Gate can even be climbed for views of the fortress and the city.
Among other sights inside the fortress an old Turkish Hamam, the Bali-Beg Mosque and a collection of Roman sculptures can be found.
Nowadays the Nis Fortress is mainly used as a recreation area with many restaurants, cafes and galleries.
The Nis Fortress dominates the right bank of the river Nisava. The main entrance is the Istanbul gate which can be reached by crossing the bridge from the square Trg Kralja Milana.
A large park area enclosed by the fortress walls. Plenty to do here from sitting on a shady bench and watching the world pass to childrens rides and several bars for refreshments.
Spent a couple of hours relaxing here on a warm day.
At the entrance to the Fortress from the city centre (there's actually a second entrance on the opposite side of the Fortress from the suburbs) there's a large building with one room labelled "Serbian Souvenirs". Although the souvenirs are nice, and its pretty difficult to find a similar shop somewhere else in town, the real artwork is in the large room beside the shop. You'll notice the beautiful Ottoman seal that has been carved above the door and the surly looking man who sits out front. There is no entrance fee and the artwork itself is primarily contemporary works that are by Serbian artists. Its a great way to get a feeling for what contemporary culture is like in Nis, as the town can sometimes feel rather sleepy.
In the centre of the Fortress you'll find a collection of grave stelae that clearly predate the end of Ottoman rule, although it is unclear whether or not the pre-date Ottoman rule entirely (I'm not an expert on these things). They are Christian relics - they have pictures of people on them, which would have been haram under sharia - and are arranged nicely in a circle for your viewing pleasure. The markers have some quite interesting traits and are very much reminiscent of Roman or Hellenic style stelae that you see in the museums at Thessaloniki or Athens. Some of them are quite large and, as such, we can probably assume they once belonged to the wealthy classes of this very ancient city.
The Fortress has a number of interesting buildings, none of which is really adequately explained for them to be big tourist draws. Nevertheless, it is easy to see how the grounds were used and re-used, as there is a collection of both Ottoman structures and later works that are obviously of Balkan origin. One of my favourite was a building that appeared to have some sort of hammam attached to it, although there was no minaret (which made me believe that it wasn't in fact a mosque). There are others, including some ramshackle Serbian-style bungalows, and the only way to discover them is to simply wander throughout the park.
Sadly, the Hammam at the Fortress of Nis is not a tourist site and you cannot simply enter and take pictures. Rather, it is now a café that is frequented by families (there are many cafés at the entrance to the Fortress from the centre of town). Nevertheless it is still possible to admire the architecture from afar.
The Fortress is the most prominent tourist site in Nis and it is likely the one that draws the most visitors. The former Turkish military site is now a large park with restaurants and activities for children with little to no explanation about the historical significance. Nevertheless, the ruins of the Ottoman buildings is fairly well maintained and it provides an excellent opportunity for anyone who wants to walk around a green and beautiful area while still feeling like their doing something educational.
The Fortress rises on the right bank of the Nisava River, overlooking the area inhabited for longer than two milleniums.The extant fortification is of Turkish origin, dating from the first decades of the 18th century (1719-1723). It is well-known as one of the most significant and best preserved monuments of this kind in the Mid-Balkans. The Fortress was erected on the site of earlier fortifications - the ancient Roman, Byzantine, and later yet Mediaeval forts.
Almost everyone who has been to Nis chose the fortress as a "must see" recomendation, and for a good reason: it has historical significance, as well as the best view on the town :) Still, it is something even more than that- it is a place where you can be in the midst of the town and yet so far away from all the hustle. How many cities can boast with THAT? :)
inside the fortress there is a monument to Milan Obrenovic, liberator of from the Turkish rule. it was errected in the late 1870's. It's too small and ordinary in my opinion, I think ti should be more pomopous!