Budapest's Cittadella is a fortification on top of Gellért Hill in Budapest, Hungary. The fort was built in 1851 by the commander of the Austrian Empire, Julius Jacob von, and the fort occupies almost the entire 235-meter high plateau. The fortress is a U-shaped structure built around the central courtyard, 220 meters long, 60 meters wide and 4 meters high. It has 60 cannons. It is very flavorful to walk around, no need to buy tickets.