Aššur, also known as Ashur and Qal'at Sherqat, was the capital of the Old Assyrian city-state (2025–1364 BC), the Middle Assyrian Empire (1363–912 BC), and for a time, of the Neo-Assyrian Empire (911–609 BC). The remains of the city lie on the western bank of the Tigris River, north of the confluence with its tributary, the Little Zab, in what is now Iraq, more precisely in the al-Shirqat District of the Saladin Governorate.
Occupation of the city itself continued for approximately 3,000 years, from the Early Dynastic Period to the mid-3rd century AD, when the city was sacked by the Sasanian Empire. The site is a World Heritage Site and was added to that organisation's list of sites in danger in 2003 as a result of a proposed dam, which would flood some of the site. It has been further threatened by the conflict that erupted following the US-led 2003 invasion of Iraq. Assur lies 65 kilometres (40 mi) south of the site of Nimrud and 100 km (60 mi) south of Nineveh.