Birtha (Mesopotamia) bastions are quite traceable. There are the ruins of a vaulted secret staircase, leading down from the heart of the citadel to the water's edge. Birtha (Mesopotamia) Birtha () was an ancient fortress on the river Tigris, which was said to have been built by Alexander the Great. It would seem, from the description of Ammianus, to have resembled a modern fortification, flanked by bastions, and with its approaches defended by out-works. Shapur II here closed his campaign in 360, and was compelled to retire with considerable loss. D'Anville and Edward Gibbon both identify Birtha as modern-day Tikrit, Iraq. The
History of Mesopotamia often dubbed the cradle of civilization. The rise of the first cities in southern Mesopotamia dates to the Uruk period, from c. 4000 BC onward; its regional independence ended with the Achaemenid conquest in 539 BC, although a few native neo-Assyrian kingdoms existed at different times. Mesopotamia literally means "(Land) between rivers" in ancient Greek. The oldest known occurrence of the name Mesopotamia dates to the 4th century BC, when it was used to designate the land east of the Euphrates in north Syria. Later it was more generally applied to all the lands between the Euphrates and the Tigris,