Despot Gate and Castellan Tower is often referred as to Eastern Upper town’s Gate. During the Middle Ages this was the main entrance to the Belgrade’s Fortress. Alongside with the north-eastern rampart, it represents the best preserved segment of the medieval Upper Town dating from the first half of the fifteenth century. The Despot’s Gate, which is the only one preserved in its original state, consisted of double ramparts, two gates – one corresponding to the inner and other to the outer rampart.

The inner gate had a defensive balcony – ‘masikula’. Underneath there was a niche for the icon of the woman protector of the town. Beside the gate there is also a massive quadrangular Castellan’s Tower. It owns its name to the fact that it was the home of a castellan – Fortress commander in the eighteen century. This tower was severely damaged during the bombing of Belgrade in 1915. It has been partly reconstructed in 1938. At the end of the seventies of the last century, the tower’s top and tines were reconstructed. The Castellan’s Tower currently houses the Observatory of the Astronomical Society “Rudjer Boskovic”.