Start the tour at 9 am when the Nis tour guide will take you from your hotel. The travelling time to Nis is about 2 hours. The town is known as the birthplace of the famous Roman Emperor Constantine the Great.

Make the first stop at the skull tower (Chele Tower). It is a stone structure embedded with human skulls located in Nis, Serbia. It was constructed by the Ottomans following the Battle of Cegarof May 1809, during the First Serbian Uprising.

Next, head towards the former concentration camp. It was opened in 1941 during World War II and used to hold captured communists and Jews. More than 10,000 people are thought to have been killed at the camp. It currently functions as a museum.

Proceed to the final stop at the City Museum in Nis. There are archaeological findings in the area displaying the history of the town.

After the guided tour around all the monuments, you are going to take a walk past the central pedestrian street, where you can find different type of local shops and delicious food. You will have around an hour and a half of free time after which you will return to Sofia around 6 pm.