Matthew 24:2
But he answered them: you see all these, do you not? Truly, I say to you, there will not be left here one stone upon another that will not be thrown down. The prediction of the temple's total destruction — not one stone upon another — is the historical prophecy that the Olivet Discourse will elaborate. The prophecy was fulfilled in 70 AD when the Roman general Titus destroyed the temple and left the foundation stones bare. The disciples' question in verse 3 reveals that they connected the temple's destruction with the end of the age.