Sliven is famous for its Bulgarian Haiduts who fought against the Ottoman Turks in the 19th century and is known as the "City of the 100 Voyvodi", a Voyvoda being a leader of Haiduts.

The famous rocky massif Sinite Kamani (Сините камъни, "The Blue Rocks") and the associated national park, the fresh air and the mineral springs offer diverse opportunities for leisure and tourism.

Another point of interest and symbol of the city, as featured on the coat of arms, is the thousand-year-old Stariya Briast (Старият Бряст, "The Old Elm"), a large Smooth-leaved Elm in the center of the city. During the time of the Ottoman Occupation, Turkish officials would hang Bulgarian revolutionaries on the tree. In modern times, the city is doing its best to keep the tree alive with the addition of cement to the base.