Babylon is located in Iraq in Old Testament. In the New Testament, where is the "mystery, Babylon" in Revelation 17-5?

The name written on the forehead of the woman riding the scarlet colored beast did not represent a location nor did it refer to literal Babylon located in Iraq in ancient times.  Rather it was part of a title,  “MYSTERY: BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH”. The title symbolically identified the woman.

All of Revelation is filled with signs, symbols, and pictures from the vision the Apostle John received on the isle of Patmos. These visions were delivered to him by Our Lord Jesus, Himself.  Given the symbolic nature of the book, you can see the Revelation 17 vision does not refer to a literal woman riding a scarlet colored beast, nor was her head literally inscribed with a title, nor was that Babylon a literal city.  The woman is a symbol.

Where else in the Scriptures do we find a woman as a symbol?  In the parable of the wise and foolish virgins given by our Lord in Matthew 25. Here the true bride of Christ is represented as the wise virgins who go out to meet the bridegroom.  They represent the pure church, the true church. In the opposite sense, the woman in Revelation 17:5 represents a false and evil church as shown by her description. She was arrayed in purple and scarlet and decked with gold and precious stones and pearls.  Does this remind you of any church you may know that displays various forms of wealth in both person and ritual?  In her hand was a golden cup full of the abominations and filthiness of her fornication.  Who was she fornicating with?  Rev 17:1,2 says that she was a prostitute and had committed fornication with the “kings of the earth!”  Since the time of our Lord’s first advent, has there been a church which has made strong alliances with the kings of the earth, the earthly governments throughout history?

Why does her title include the name, Babylon?  Smith’s Bible Dictionary tells us that Babylon is the Greek form of Babel.  You may recall the account of the tower of Babel in the Old Testament where God confused the language of the people so that they could not complete the construction of the tower.  Indeed, the name Babylon means the same as its real reference, that is, confusion.   

This false church system carries in her hand, a cup that was once filled with truth, but now is contaminated with a wide array of confusing doctrines. Those doctrines are designed to intoxicate those who drink it.  As error was spread, ambition replaced the spirit of humility and loyalty to God and she desired the conditions that would give her greater power and influence in the world.  Revelation 18 describes in detail the destruction of this false system.