Diyarbakir Castle or Diyarbakir walls is a historical building located in the Sur district of Diyarbakir. It consists of two parts, the inner castle and the outer castle. The main entrances on the walls are Dağ Kapı, Urfa Gate, Mardin Gate and New Gate. The walls, which are about nine thousand years old, are the longest and widest defensive wall in the world after the Great Wall of China. UNESCO included the building on the World Heritage Tentative List in 2000, and registered it as a World Heritage Site in 2015. In addition, the Goat Bastion, which is a very old structure of Diyarbakır, is located in the district of Sur. The walls consist of two parts, the Inner and the Outer Castle.