Ur, situated in southern Sumeria, was a most magnificent city at the time of Abraham, with a population of 24,000. It was a centre of manufacture and farming. It was a sea port at the mouth of the Euphrates onto the Persian gulf, with trade to India and Africa. It had two dock areas, one for the city, and one for the temple. The river later silted up and changed its course, so the sea became further away. Ur lost its source of trade so became ruined, its place being taken by Babylon. It was a centre of advanced culture, where libraries of tablets containing business documents and contracts, hymns and liturgies have been found. The houses were built of brick, had two floors, with an inner courtyard, central heating, and with a sewerage system from each house.
The ancient city of Ur was excavated by Sir Leonard Woolley in 1923. There were 45 fortified cities on Persian flood plain, dating back to around 2700 BC. Abraham was born there around 1800 BC, so Ur was nearly as old to him as London is to us! (900 years)
Terah took his son Abram and his grandson Lot son of Haran, and his daughter-in-law Sarai, his son Abram's wife, and they went out together from Ur of the Chaldeans to go into the land of Canaan ... (Gen 11:31)
It had a ziggurat (temple tower) like the tower of Babel. It was a centre of polytheistic idolatry, which Terah was involved with:
And Joshua said to all the people, "Thus says the LORD, the God of Israel: Long ago your ancestors - Terah and his sons Abraham and Nahor - lived beyond the Euphrates and served other gods. (Josh 24:2)