World's Most Difficult Jigsaw Puzzle

I thought I had found some hard jigsaw puzzles in my day but boy was I mistaken. One tough puzzle is a puzzle that only has nine pieces but has 300,000 wrong ways to put it together and only one right way. I thought this was the most difficult jigsaw puzzle in the world. Then I found a 500 piece jigsaw puzzle that is double-sided. It has the same picture on both sides, rotated 90 degrees from each other. Jigsaw puzzles are cut in a press stamped out like cookie dough. That is why the top of the puzzle has a groove and the bottom is flat. Now having a double sided puzzle will make any puzzle hard, but any savvy puzzler would easily pick up on this and would be able to tell which side is up and which side is down. Well guess what, there is still another twist to these puzzles. These puzzles are cut once from each side. The vertical locks are cut from the front and the horizontal locks are cut from the back. Now there is no way to tell which side is which! You have to compare both sides of each piece. If the piece doesn't fit exactly, you've got it wrong. I believe this is the world's most difficult puzzle. I bet you can't wait to try this one can you?