Exegesis:

tauta ha theōreite lit. ‘these things which you see,’ aposiopesis, since it is not taken up by a clause of which tauta is a part. It is best rendered independently, ‘as to these things which you see.’

eleusontai hēmerai en hais ‘days will come in which…,’ cf. on 5.35.

en hais ouk aphethēsetai lithos epi lithō ‘in which, i.e., when no stone will be left upon another.’ For aphiēmi cf. on 19.44.

hos ou kataluthēsetai ‘that shall not be thrown down,’ as if preceded by ouk estin lithos ‘there is no stone….’ As the clause stands it has the semantic function of stating positively what was expressed negatively by ouk aphethēsetai lithos epi lithō.

kataluō here ‘to throw down,’ ‘to detach from its place.’

Translation:

As for these things which you see. The subsequent break in the sentence structure is best marked by a dash or dots. Where such a break would be unacceptable one may connect the phrase with what follows, cf. e.g. ‘what you see there, the days will come that no stone of it…’ (Leyden), ‘such days will come, that what you are looking at, of it no stone…’ (cf. Marathi).

There shall not be left here one stone upon another, or in active construction, ‘they (or, the enemies) will not leave…,’ cf. on 19.44.

That will not be thrown down is often better translated as a new sentence, e.g. ‘everything (or, every stone) will be cast down.’

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.