 Part of the Antonian hill to the north of Moriah was annexed to the complex and the area between was filled up with landfill.The project began with the building of giant underground vaults upon which the temple would be built so it could be larger than the small flat area on top of Mount Moriah.Ground level at the time was at least 20 ft. (6m) below the current level, as can be seen by walking the Western Wall tunnels.