John Gill Commentary Mark 13:4

"Tell us, when shall these things be? and what [shall be] the sign when these things are all about to be accomplished?" — Mark 13:4 (ASV)

Tell us when shall these things be ?
&c.] When the temple will be destroyed, and these fine buildings shall be demolished, and not one of these large stones shall be left upon another:

and what shall be the sign when all these things [shall be]
fulfilled ?
And what is the sign of his coming, and of the end of the world, as Matthew relates; (See Gill on Matthew 24:3).