This is the largest and I have actually been there:
Photograph of Ball of Twine from Cawker City Kansas
That was thoughtful of the biggest ball of twine people to provide benches so visitors can sit and look at the twine and think about it.
But after pondering the twine, and all the nefarious uses to which twine can be put, it seems reckless as well, tempting visitors to commit mental twine crime.