The main city of Southern Serbia is Nish, the birthplace of emperor Constantine the Great, a city that boasts the remnants of the Roman town of Mediana as well as the eerie skull-tower known as Cele-Kula. The Devil's Town, a rare geological phenomenon near the town of Kurhumliya, consists of hundreds of stone pillars topped with wide flat rocky caps. Poganovo monastery is famous for its mysterious fresco of St. Christiphore with a donkey's head. The southern Serbian town of Vranje is the place to go for experiencing the genuine architecture and vibes of once powerful Ottoman Empire. The Yerma canyon is a good place to visit for some trekking and eagle-spotting.