Nis; Serbia; Cele Kula (skull tower) detail. The skull tower was made from the skulls of Serbian patriots defeated by Turks after a battle in 1809. It contained nearly 1000 skulls and was meant as a warning to help deter Serbian resistance and insurrection. After Nis was liberated; it was treated as a patriotic monument and war memorial; even though it was extremely dilapidated. Its walls are not extremely deteriorated; and few skulls remain. It is protected behind glass. This photo shows a close-up of the surface. Photo 2010.