Ur is an important city-state in ancient Sumer located at the site of modern Tell el-Muqayyar in Iraq's Dhi Qar Governorate.

Once a coastal city near the mouth of the Euphrates on the Persian Gulf, Ur is now well inland, south of the Euphrates on its right bank, 16 kilometers (9.9 mi) from Nasiriyah.The city's patron deity is Nanna, the Sumerian moon god, and the name of the city is in origin derived from the god's name, literally "the abode (UNUG) of Nanna (LAK-32)".

The site is marked by the ruins of the Great Ziggurat of Ur, which contained the shrine of Nanna, excavated in the 1930s.

The temple was built in the 21st century BCE (short chronology), during the reign of Ur-Nammu and was reconstructed in the 6th century BCE by Nabonidus.

The ruins cover an area of 1,200 meters (3,900 ft) northwest to southeast by 800 meters (2,600 ft) northeast to southwest and rise up to about 20 meters (66 ft) above the present plain level.