Difficult puzzles

The complexity of a jigsaw puzzle largely depends on two things - the size of the puzzle, and the colour of the design, or a combination of them. The Worlds Largest Jigsaw, 24,000 pieces relies on considerable patience by virtue of its share size, although the pattern itself is bright and colourful and not too difficult.
In a puzzle such as Lunchtime 1932, 1000 pieces, the pieces are shades of black and white, and so it is very difficult to complete.

No matter what your age or puzzle ability, the more challenging the jigsaw, the more rewarding on completion. What is the most difficult puzzle you have ever put together?? Click on comment below, and let us know.