Here\’s to the attempt…
[youtube http://www.youtube.com?v=GPjddqhB7f8]
From the description:

This would have been the biggest 3D domino pyramid on YouTube and very probably in the world (not a Guinness record though, they don\’t have such a category yet), with a bottom layer of 27×27 and 13,482, but there seems to be some kind of Egyptian curse on domino pyramids. I didn\’t even make a mistake here, it toppled all by itself when it was more than 96% completed, with just 439 dominoes missing 🙁
So 13,043 were standing when it toppled, which makes this my new personal domino record, beating the old one by almost 4,500 pieces! It\’s the first time I have toppled more than 10,000 dominoes, and more than the 11,111 that made the first world record in 1974.