Erzurum Castle occupies the low hill at the heart of the old city. The first fortification here is usually traced to the Byzantine period, though much of what remains is Seljuk and later repair.
Climb the Tepsi Minaret watchtower for the best view over the city, the madrasas below, and the mountains beyond. The castle is more fragmented than imposing, but its position makes Erzurum's geography obvious.