On the pinnacle of the Temple stands a Tau cross.  Severe weather caused the breaking off of the top of the original Roman cross.  After learning about the deep significance of the Tau cross, which is the form of the Greek letter "T", Mother Angelica saw this "accident" as a work of Divine Providence and decided not to repair the weather damage!  The Tau Cross is the sign Our Lord had His angel mark upon the foreheads of the faithful people (Ezekiel 9:4).  It is also the cross that Saint Francis preferred, using it as the signature for his writing.  Finally, it is the symbol of spiritual renewal in the Church.