Go into the whole world and proclaim the gospel to every creature.
Mk 16:15-20
THE ASCENSION ACCORDING TO ACTS
The
 ascension took place 40 days after the Resurrection. During that time 
Jesus through his appearances proved that he was alive. He instructed 
his apostles about the Kingdom and told them to wait in Jerusalem for 
the coming of the Holy Spirit. When he comes, they will become his 
witnesses, first in Jerusalem, then in Palestine, and finally to the 
ends of the earth. Even after instructing them for 40 days, they still 
did not understand Jesus and his mission. For if they understood, they 
would not ask: “Lord, are you at this time going to restore the kingdom 
to Israel?” Until now they were still thinking of Jesus and the Kingdom 
in terms of earthly power.
The ascension is described as Jesus rising
 towards heaven and then being hidden by the clouds. Two men in white 
garments (angels) tell the disciples that the Parousia (return of Jesus)
 will happen in the same way.
In the Acts of the Apostles it seems that the ascension took place somewhere in the vicinity of Jerusalem.