The Smederevo Fortress (Serbian: Cмeдepeвcκa твpђaвa, Smederevska tvrđava), in Smederevo, Serbia, was a medieval fortified city and temporary capital of Serbia in the Middle Ages. It was built between 1427 and 1430, on the order of Despot Đurađ Branković, the ruler of the Serbian Despotate. It was further fortified by the Ottoman Empire, that had taken the city, in the end of the century. Smederevo is the largest medieval lowland type of fortresses in Europe.
The fortress withstood several sieges between the Ottomans and Serbs, which it survived relatively unscathed. It was not until World War II that it was heavily damaged, by explosions and bombing. As of 2009 it is in the midst of extensive restoration and conservation work, despite which the fortress remains "one of the rare preserved courts of medieval Serbian rulers."
Smederevo Fortress was declared a Monument of Culture of Exceptional Importance in 1979, and is protected by the Republic of Serbia. In 2010, the fortress was placed on the Tentative List for possible nomination as a World Heritage Site (UNESCO).