The building's enclosure wall is built the same way as the platform in Jerusalem that supports the Dome of the Rock, by the same ruler, for a grave whose purchase price the Bible actually records.
A purchase, not a gift
Genesis describes Abraham purchasing the cave and the field around it from Ephron the Hittite for four hundred shekels of silver, specifically as a burial place for his wife Sarah, a transaction recorded in enough commercial detail, including Abraham's insistence on paying full price rather than accepting the land as a gift, that the episode is often read as establishing a legal claim as much as a religious one. Tradition holds that Isaac, Rebekah, Jacob and Leah are also buried within the same site.
Herod's enclosure
The massive stone enclosure wall surrounding the cave, built from huge finely dressed ashlar blocks, is attributed to Herod the Great, using construction techniques closely comparable to his expansion of the Temple Mount platform in Jerusalem, making Hebron's enclosure one of the best-preserved examples of Herodian monumental building anywhere, largely intact despite the site's long and often violent subsequent history.
A shared floor plan, not a shared entrance
Since the 1994 division that followed the massacre covered elsewhere in this entry's companion article, Muslim and Jewish worshippers use separate sections and separate entrances within the same Herodian structure, with each community's access to specific chambers governed by a fixed schedule that changes on Jewish and Muslim holidays.