Located in the center of Erzurum, Erzurum Castle is one of the oldest and most impressive structures in the city. Built during the Byzantine period, the castle was used by the Seljuks, Ottomans and other civilizations throughout history. The inner castle draws attention with its sections such as ramparts, watchtowers and clock tower. The inner castle, which still exists today, was built by the Byzantine Emperor Theodosius in 415. There is a brick bathhouse and rooms in the courtyard of the inner castle. During the Ottoman Empire, the Inner Castle Mosque was built next to the northern wall of the inner castle. The Kırklar Tomb, the Ebu İshak-ı Kâzerûnî Tomb and the Ali Ağa Fountain were also added to these structures. Offering a panoramic view of the city, the castle is a treasure of Erzurum waiting to be discovered with both its historical texture and magnificent atmosphere.