David's Been Here is traveling through Serbia in search of the top destinations and best attractions. In this travel clip, David brings us the top things to see and do in the southern city of Nis, Serbia's third largest city, Nis is one of the most historically significant destinations in the entire country with loads of sites, attractions and monuments to show for it. From ancient historical sites such as the 1st century, Roman-built Nis Fortress and the surrounding 2,000-year-old Roman tombstones to more modern historical stops including a German concentration camp from World War II, Nis is a veritable open history book. Make sure to stop by the chapel-protected Skull Tower (an infamous Ottoman creation after defeating the Serbs), the incredible Archaeological Hall of Nis and the site of the start of World War I. With beautiful walking streets and some modern attractions worth visiting as well, travelers stopping over in Nis will have no shortage of things to do!