Matthew 24 : 29 - 30 : Immediately after the distress of those days the sun will be darkened and the moon will lose its brightness, the stars will fall from the sky and the powers of the heavens will be shaken. And then the sign of the Son of Man will appear in heaven; then too all the peoples of the earth will beat their breasts; and they will see the Son of Man coming on the clouds of heaven with power and great glory.
Now what you have referred to is Matthew 24 : 34, which follows 33 which says : So with you when you see all these things: know that he is near, at the very gates. then 34 goes on to say :I tell you solemnly, before this generation has passed away all these thing will have taken place.
Note that all this follows Matthew 24 : 20 - 22
Matthew 24 <SUP>20-22</SUP> (King James Version)
But pray ye that your flight be not in the winter, neither on the Sabbath day: for then shall be great tribulation, such as was not since the beginning of the world to this time no, nor ever shall be. And except those days should be shortened, there should be no flesh be saved: but for the elect’s sake those days shall be shortened.
This all refers to the "Destruction of Babylon" and I deal with all of this in my scripture studies documents; but I do not yet have enough posts at this site to qualify for posting images of photographed documents.