In the eighteenth year of his reign (20–19 BCE), king Herod the Great (74/73 BCE – 4 BCE) rebuilt the Second Temple in Jerusalem on "a more magnificent scale".The new Temple was finished in a year and a half, although work on out-buildings and courts continued another eighty years.
To comply with religious law, Herod employed a thousand priests as masons and carpenters for the rebuilding. The finished temple, which was destroyed by the Romans in 70 AD, is often referred to as Herod's Temple. The Wailing Wall (Western Wall) in Jerusalem was for many years the only section visible of the four retaining walls whose construction was begun by Herod to create a flat platform (the Temple Mount) upon which his Temple was constructed. Recent findings suggest that the Temple Mount walls and Robson's Arch may not have been completed until at least 20 years after his death during the reign of Herod Agrippa II. (source of this paragraph: Wikipedia)
"When Herod built the Temple Mount courtyard he made it 485 m long and 315 m wide. The courtyard sloped southwards, and the southern part of the plat-form therefore had to be raised to keep the surface level. Herod filled in only the lower part of the space between the retaining wall and the natural slope, and built the remaining space, to the top of the platform, in the form of vaults, with their ceilings supported by pillars. The south-east corner of the Temple Mount, which had a retaining wall 48 m high, was filled with rubble and soil to a height of 32 m; over this filling was a hall, its roof forming the pavement of the courtyard, and above this rose the upper wall.
The walls of the Temple Mount were 5 m thick and consisted of enormous ashlar blocks weighing up to 150 tons. This formidable structure made the Temple into a mighty fortress, unequaled in the architecture of antiquity. Josephus writes (Antiquities XV, ): ". . . which wall was itself the most prodigious work that was ever heard of by man". The southern wall had a height equal to that of a modern fifteen-story building.
Herod constructed two halls with an area of 500 sq. m, the ceilings supported by eighty-eight pillars in twelve parallel rows with thirteen aisles between them, thus raising the level of the courtyard by 12 m. The arches were 9-10 m high, the length of the halls from east to west was 83 m and the width, from north to south, 60 m. There were additional structures which changed the shape of the halls somewhat.
During the Second Temple period these halls were entered by the Huldah Gates, and stairs led to the upper level of the Temple courtyard. When the Crusaders took Jerusalem they identified the halls of pillars as the stables of King Solomon, as did Nasir i-Khosrau and other Moslems.
The Crusaders used the halls to stable the horses of the Knights Templar, whose headquarters were in the El Aksa Mosque. The Crusaders entered their stables through the Triple and Single Gates (both now walled up), which they rebuilt.
(from Menashe Har-El, This is Jerusalem, Canaan Publishing House, PO Box 7645, Jerusalem 1977)"
Upper illustration and quoted text from Solomon's Stables and the Southern Gates by Tuvia Sagiv.
See many more illustrations on former and present day architecture of Temple walls, ancient Jerusalem and Herod's Temple here.