Very nice this place, and I visited it more than two years ago, and I liked it enormously, and now I remember that it was very difficult to find a parking place nearby, eventually I parked the car in a public parking lot and I actually could not pay my parking with the Serbian app, I had no Serbian number, but I met two young men who helped me and paid the parking from their cell phone.
There are so many beautiful places around Belgrade, especially the Sava river and many others, not to forget the food which is excellent.
RE: Festival (and some more) at Kalemegdan fortress in Belgrade