Nebojsa Tower represents the only remaining well preserved medieval building within the Belgrade Fortress. It was built around 1460 and belongs to the oldest type of early artillery canon towers. When it was built it represented an important achievement in the architecture of the time. It was built for the purpose of defending the city from the Turks and in a wider sense it represented part of the defense system – "the bulwark of Christianity" that had for decades successfully stopped Turkish invasions into central Europe. A few centuries later, when it lost its military importance it was transformed into a dungeon. At the end of the 18th and the first decades of the 19th century it represented a symbol of Turkish repression and a place of perishing of Christian warriors from the Balkans during the centuries long Ottoman rule.