Luke 21:7

And they asked him
That is, his disciples, when they were come to the Mount of Olives, and as he sat upon that, ( Matthew 24:3 ) saying, master, but when shall these things be?
when the temple shall be destroyed; and one stone shall not be left upon another; and what sign [will there be] when these things shall come to
pass?
which shows that this refers to the destruction of the temple, and so the signs following; (See Gill on Matthew 24:3).