The two witnesses of Rev 11 re-enact the death,resurrection and ascension of Jesus Christ preparing Israel's heart for the return of Christ. Rev 11 contains valuable insight to what is happening in Jerusalem during these last days before Christ's visible return, and that Israel as a nation will not escape judgment during the already ongoing Day of the Lord.

Rev 11:1, 2
1 And there was given me a reed like unto a rod: and the angel stood, saying, Rise, and measure the temple of God, and the altar, and them that worship therein.
2 But the court which is without the temple leave out, and measure it not; for it is given unto the Gentiles: and the holy city shall they tread under foot forty and two months.

reed like unto a rod

  The angel sent by God measures with a measuring stick which is also a rod. God is also measuring judgment based on the spiritual condition of what is going on in the temple, and the altar and their worship. Remember, the temple was built and priestly sacrifice and worship restored after the mass return (timeframe 2) took place when the the Ark of the Covenant reappeared. The temple was built before the rapture in timeframe 3. Rev 11 is filling in details happening during the Day of the Lord with Israel which is after the rapture and the great 3 1/2 year Christian tribulation - timeframe 4 (see chart above and below).

           See Revelations for full study

holy city shall they tread under foot forty and two months

  42 months is 3 1/2 years the city will be overrun by Gentile forces. This agrees with what Daniel was told in Dan 9:27. Antichrist would invade Israel in the middle of the 7 year treaty he makes with Israel (see Daniel's 70th week) . This 42 months then of Rev 11:2 is the last 3 1/2 years before Christ visible return in which he defeats Antichrist and His armies (see Kingdom). It is during these 3 1/2 years that Antichrist sits in the temple of God to show that he is God (2 Thess 2:4) and commits the abomination of desolation (idol of Himself in the temple (Matt 24:15-22 see Daniel 9, Daniel's 70th week).

3 And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.
5 And if any man will hurt them, fire proceedeth out of their mouth, and devoureth their enemies: and if any man will hurt them, he must in this manner be killed.
6 These have power to shut heaven, that it rain not in the days of their prophecy: and have power over waters to turn them to blood, and to smite the earth with all plagues, as often as they will.

  Notice God gives these two witnesses power to do miracles and prophesy for 1260 days which is 3 1/2 years. They do miracles like Elijah and Moses yet testify about Christ as Messiah. Some say these witnesses are Elijah and Enoch of the Old Testament that did not see death in their day. I believe one is Elijah for it is written in Malachi 4:5 that God will send Elijah the prophet before the great and dreadful Day of the Lord.

Malachi 4:5
5 Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord:
6 And he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.

  The Day of the Lord to Israel would be the last 3 1/2 years before Christ returns because of the invasion of Antichrist and his armies (see Gog and Magog). The Day of the Lord for the Gentile nations would be the last 7 years (7 trumpets/vials).

7 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.
8 And their dead bodies shall lie in the street of the great city, which spiritually is called Sodom and Egypt, where also our Lord was crucified.
9 And they of the people and kindred's and tongues and nations shall see their dead bodies three days and an half, and shall not suffer their dead bodies to be put in graves.
10 And they that dwell upon the earth shall rejoice over them, and make merry, and shall send gifts one to another; because these two prophets tormented them that dwelt on the earth.
11 And after three days and an half the Spirit of life from God entered into them, and they stood upon their feet; and great fear fell upon them which saw them.
12 And they heard a great voice from heaven saying unto them, Come up hither. And they ascended up to heaven in a cloud; and their enemies beheld them.
13 And the same hour was there a great earthquake, and the tenth part of the city fell, and in the earthquake were slain of men seven thousand: and the remnant were affrighted, and gave glory to the God of heaven.       

  The Beast (Antichrist) kills the witnesses after 3 1/2 years of testimony. Their bodies lay in the streets and the whole world watches them. This could have been only fulfilled in the day of television and the internet. The whole world makes merry and rejoices they are dead and send gifts to one another. But after 3 1/2 days, just like Jesus, their body comes back to life. They stand on their feet and they hear a voice from heaven to come up and they ascend visibly upwards as their enemies watch them by television and the internet all over the world. There was a great earthquake and 7000 died and a tenth part of the city fell (see fall of Jerusalem). Notice verse 8. These two witnesses were killed in the same city Jesus was crucified. This would have to be Jerusalem. Also notice, Jerusalem is spiritually called Sodom and Egypt. This is why God allows Antichrist to invade Israel. The spiritual state sunk to the level of Sodom and Gomorrah and the worldliness of Egypt. After these two witnesses ascend into heaven the Jews are ready to receive Christ as their Messiah. It is no surprise that the return of Christ is recorded in the following verses

Rev 11:15
15 And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.

Zechariah describes the coming of Christ to save Jerusalem

Zechariah 12:9,10
9 And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem.
10 And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and they shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn.