Its tributaries include the Great and Little Zab Rivers, which flow down from the Zagros Mountains.
On this river lies the controversial Il?su Dam and the endangered ancient city Hasankeyf. Ctesiphon and Seleucia sit on opposite banks of this river downstream from Samarra. Its tributaries include the Great and Little Zab Rivers, which flow down from the Zagros Mountains. At Qurna, it joins a more western river to form the Shatt-al-Arab. Along this river, Nineveh lies across from Mosul, and Tikrit lies farther downstream. It comprises Syria's easternmost border with Turkey, and a brief stretch of Syria's border with Iraq, whose capital, Baghdad, straddles this river's banks. For 10 points, name this river, Mesopotamia's second-longest, which joins the Euphrates.
On this river lies the controversial Il?su Dam and the endangered ancient city Hasankeyf.
{Tigris} River [or {Dicle Nehri}; or {Nahr Dijlah}]