You'll first need to collect 15 Fleur-de-lis, which is done by asking your friends to send them to you via individual requests.
The other portion of this building project will see you reaching 350 points by spending energy to do so. You can spend either one energy or blocks of ten energy at a time, with each energy point giving you one more point towards 350. You can spend all of your own energy, of course, but you can also ask friends for additional points. This is done through a general news post on your wall.
Once you've finished the French Chateau, you'll have a home worth 2,000 - 4,000 citizens. It offers 326 coins in rent once a day. Along the way, you can also finish the French Chateau! goal, which request you to place and complete the building with at least one friend's help, and collect the 15 Fleur-de-Lis. The rewards for this goal are only 3 energy, but that's understandable considering that they're all the same tasks for finishing the French Chateau in the first place.
Either way, it will be interesting to see if this way of constructing buildings will catch on with players, and will be seen in future features, or if players will wish to just collect building materials as usual. We'll make sure to let you know which one is the case.
What do you think of the French Chateau and the new way to complete buildings in CityVille? Sound off in the comments.