Belgrade Fortress (Serbian Cyrillic: Београдска тврђава, romanized: Beogradska tvrđava), consists of the old citadel (Upper and Lower Town) and Kalemegdan Park (Large and Little Kalemegdan) on the confluence of the River Sava and Danube, in an urban area of modern Belgrade, the capital of Serbia. It is located in Belgrade's municipality of Stari Grad.