Nis; Serbia; old postcard of the Cele Kula. 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. It was enclosed by a church in 1892; so this photo dates before that time.