East of Triple Gate and beyond the east wall of the Temple House, in the far SE corner of the Temple Mount, are the terraced substructures referred to as Solomon's Stables, a name given to this substructure by the Crusaders in the 12th century, because it is where they stabled their horses. When Solomon built his porch, east of the Temple House, this section of the Temple Mount rectangle did not exist. This would have been the area described by Josephus as being like a precipice with a steep decline down into the Kidron Valley. These terraced underground vaults were not part of Solomon's Temple, or Zerubbabel's Second Temple, or Herod's Temple. This may have been built by Herod's heirs, some time after his death. Archaeologists have identified the stones used in the construction of the vaults as being recycled stones from Herod's era. Given this evidence, some believe this substructure to have been built by Emperor Hadrian when he built the Temple of Jupiter, on the Temple Mount, in 135 C.E.