The Pool of Siloam refers to a rock-cut pool on the southern slope of the City of David considered by archaeologists to be the original site of Jerusalem; located outside the walls of the Old City to the southeast. The pool was fed by the waters of the Gihon Spring, carried there by the Siloam Tunnel.
During the Second Temple period, the Pool of Siloam was centrally located in the area known as the Lower City. Today, the Pool of Siloam is the lowest place in altitude within the historical city of Jerusalem. The ascent from it unto the Temple Mount meant a gain of 115 meters (377 ft) According to the Jerusalem Talmud the Pool of Siloam was the starting point for pilgrims who made the annual pilgrimage to Jerusalem; and where they ascended by foot to the inner court of the Temple Mount to bring their sacrificial offerings.
The pool of Siloam During the Time of King Hezekiah
The Pool of Siloam was built during the reign of Hezekiah (715–687/6 BCE); to leave besieging armies without access to the spring’s waters. The pool was fed by the newly constructed Siloam tunnel. An older Canaanite tunnel had been very vulnerable to attackers, so, under threat from the Assyrian king Sennacherib; Hezekiah sealed up the old outlet of the Gihon Spring and built the new underground Siloam tunnel in place of the older tunnel (2 Chronicles 32:2–4).
The pool of Siloam: Second Temple Period
The pool was reconstructed no earlier than the reign of Alexander Jannaeus (103-76 BCE); although it is not clear whether this pool was in the same location as the earlier pool built by Hezekiah — if so, all traces of the earlier construction have been destroyed. The pool remained in use during the time of Jesus. According to the Gospel of John; Jesus sent “a man blind from birth” to the pool in order to complete his healing.
As a freshwater reservoir, the pool would have been a major gathering place for ancient Jews making religious pilgrimages to the city. Some scholars, influenced by Jesus commanding the blind man to wash in the pool; suggest that it was probably used as a mikvah (ritual bath). However, mikvahs are usually much smaller in size; and if the pool were a mikvah, it would be the largest ever found by a substantial margin.
The pool was destroyed and covered after the First Jewish–Roman War in the year 70. Dating was indicated by a number of coins discovered on the stones of the patio near the pool to the north, all from the days of the Great Revolt. The latest coin is dated with “4 years to the day of the Great Revolt”, meaning the year 69. In the years following the destruction, winter rains washed alluvium from the hills down to the valley and down the slopes of Mount Zion to the west of the pool; the pool was filled with silt layers (up to 4 m in some places) until it was covered completely.