Jesus answer to his disciples was that one stone would not remain upon another in the future. He was predicting what would happen to the current temple they were looking at. This actually came true in AD70 and still remains that way to this day. There is no temple standing there now. The Roman soldiers set fire to the temple and the gold melted and ran down into the stones. In order to get the gold, the soldiers took it apart stone by stone until there was not one stone left standing upon another. So the statement of Jesus literally came true just as he said.
When the disciples asked when it would be, Jesus answered with the fact that many would come in His name and there would be wars and rumors of wars. He then tells them how His followers would be persecuted and this has happened clear up until our current day. The hatred of Jesus and his followers is still there. We are feeling this hatred for Christ and his true followers even in America today despite our so called religious freedom. It is far worse in many other countries today. How much am I known as a follower of Jesus today? It is only going to get worse and particularly after Christ returns for his church in the rapture when the tribulation starts.