Albert Barnes Commentary Luke 13:4

"Or those eighteen, upon whom the tower in Siloam fell, and killed them, think ye that they were offenders above all the men that dwell in Jerusalem?" — Luke 13:4 (ASV)

Or those eighteen. Jesus himself adds another similar case to warn them — a case which had probably occurred not long before, and which it is likely they judged in the same manner.

Upon whom the tower in Siloam fell. The name Siloah or Siloam is found only three times in the Bible as applied to water — once in Isaiah 8:6, who speaks of it as running water; once as a pool near the king's garden, in Nehemiah 3:15; and once as a pool, in the account of the Saviour's healing the man born blind, in John 9:7-11.

Josephus frequently mentions the fountain of Siloam as situated at the mouth of the Valley of Tyropoeon, or the Valley of Cheesemongers, where the fountain, long identified as that particular one, is still found. It is on the south side of Mount Moriah, and between that mountain and the Valley of Jehoshaphat.

The water currently flows out of a small artificial basin under the cliff and is received into a large reservoir 53 feet long by 18 feet wide. The small upper basin or fountain, excavated in the rock, is merely the entrance, or rather the termination, of a long and narrow subterranean passage beyond, through which the water comes from the Fountain of the Virgin.

For what purpose the tower referred to here was erected is not known; nor is it known at what time the event referred to here occurred. It is probable that it was not far from the time when the Saviour used the illustration, for the manner in which he refers to it implies that it was fresh in the recollection of those to whom he spoke.