According to the Fatima Movement not to be confused with the Fatima Movement of Priests, by way of the Portuguese American Journal, the vatican will be destroyed on August 17, 2011.
Now that is not completely impossible. Italy (and more specifically the Lazio region) have had some pretty bad earthquakes, and a moderate to strong earthquake could take out the Vatican, I guess.
As for terrorists- well, they don't have too tight a wall of security, but there is this: Not even the gates of hell shall stand against it, and what are terrorists if not from hell.
As for Our Lady authorizing the destruction of the her Son's Church- meh.
Scripture to keep in mind
Six things there are, which the Lord hateth, and the seventh his soul detesteth:  Haughty eyes, a lying tongue, hands that shed innocent blood,  A heart that deviseth wicked plots, feet that are swift to run into mischief, A deceitful witness that uttereth lies, and him that soweth discord among brethren.  My son, keep the commandments of thy father, and forsake not the law of thy mother. ***Cf:Douay-Rheims Proverbs 6: 16-20
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