The disciples consider the destruction of Jerusalem to go hand in hand with the coming of the Christ in glory and the end of the current age.1 In response to Jesus’ comment that the temple will be destroyed they want to know when it will happen and what signs will precede it. They want to know what they must look out for so that they can be ready for the closure of redemptive history.2
In his answer to them, Jesus will give lots of general/imprecise signs which imply that they must always be ready.3
3 As he sat on the Mount of Olives, the disciples came to him privately, saying, “Tell us, when will these things be, and what will be the sign of your coming and of the end of the age?”