As Jesus was sitting on the Mount of Olives, the disciples came to him privately.
"Tell us," they said, "when will this happen,
and what will be the sign of your coming and of the end of the age?"

Matthew 24:3
(from New International Version)

And Jesus, answering them,
began to say:
"Take heed that no one deceives you.
For many will come in My name,
saying, 'I am He,'
and will deceive many.
But when you hear of wars
and rumors of wars,
do not be troubled;
for such things must happen,
but the end is not yet.
For nation will rise against nation,
and kingdom against kingdom.
And there will be earthquakes in various places,
and there will be famines and troubles.
These are the beginnings of sorrows."

Mark 13:5-8
NKJV

"Now learn this lesson from the fig tree:
As soon as its twigs get tender and its leaves come out,
you know that summer is near. Even so, when you see these things happening,
you know that it is near, right at the door. 
I tell you the truth, this generation will
certainly not pass away until all these things have happened. 
Heaven and earth will pass away, but my words will never pass away."

Mark 13:28-31
(from New International Version)