Ur Kasdim (Hebrew: אוּר כַּשְׂדִּים‎ ʾūr Kaśdīm), commonly translated as Ur of the Chaldeans, is a city mentioned in the Hebrew Bible as the birthplace of the Israelite and Ishmaelite patriarch Abraham. In 1862, Henry Rawlinson identified Ur Kaśdim with Tell el-Muqayyar, near Nasiriyah in southern Iraq. In 1927, Leonard Woolley excavated the site and identified it as a Sumerian archaeological site where the Chaldeans were to settle around the 9th century BC. Recent archaeology work has continued to focus on the location in Nasiriyah, where the ancient Ziggurat of Ur is located.

Other sites traditionally thought to be Abraham’s birthplace are in the vicinity of the city of Edessa (Şanlıurfa in modern south eastern Turkey). Traditional Jewish and Muslim authorities, such as Maimonides and Josephus, placed Ur Kaśdim at various Upper Mesopotamian or at other southeast Anatolian sites such as Urkesh, Urartu, Urfa, or Kutha.