what is the most unbreakable bike frame around?

Due to a long, sordid history of breaking frames, i thought i'd ask for everyones opinion on the strongest, most reliable bike frame they have ever had.

Mine would have to be the Giant CFR1 road frame. I bike couriered on this sucker for 5 years and it never gave an inch, and it lasted 4 years longer than any other frame i ever had.
It has been retired to the wall in my laundry where it will remain out of respect for its resilience.