My son age four made this Eiffel tower with some help from my sister. We had to use glue to stick it together so kids would break it. Bottom pieces did fall when my (age four) son try to build next piece above it. Anyway he had fun with it and now it is a decoration pieces for his room. He shows it to EVERYONE who enters our home. He is so proud of it. I think age six and up probably will have more fun making it because they will be doing most of the work independently with less help from an adult.
We purchased this puzzle for our daughter for a school project. It was fairly durable however, she would never have been able to put it together without help and she's 14. You definitely need two sets of hands. Also, it doesn't stay together on its own, so we had to glue it to keep it from falling apart. Once we did that, it looked great.
My students have completed 8 or 9 wooden puzzles recently and this one has been of the worst quality. The wood broke easily, was warped, and didn't fit together well. I will avoid purchasing puzzles made by this company. The ones made by "Creatology" are much better.