John Lightfoot on Luke 13:4

[Upon whom the tower in Siloam fell.] The poor of Bethesda was the pool of Siloam; and from thence all that adjacent part of the city is denominated Siloam. And therefore it is left doubtful, whether this tower were built over the pool, that is, over the porches of the pool, or stood something remote from it in those parts that yet bore the name of Siloam. And if the article in does not determine the matter, we must continue still in doubt. Will grammar permit that that article should be prefixed to that part of the city? It is certain, that the very pool is called the pool of Siloam. So that I conceive this tower might be built over the porticoes of the pool, and might overwhelm those eighteen men, while they were busied about purifying themselves (and so this event falls in the more agreeably with that of the Galileans), or as they were expecting to be healed at the troubling of the waters: for it is very uncertain at what time this tower fell.