What is the longest that you've ever spent on a project and what was it?

How did it turn out?
When I was a teen, I once spent one whole year on a needlework for my mother. She loved medieval stuff and I did a large needlework picture of a wizard. It was very complex, which is why it took months, and I spent almost all night on Christmas Eve hurrying up and getting the small details done.
It was definitely worth it in the end though, because my mom LOVED it to bits. She was so proud of me and would show everyone who came over!