This achievement is for completion of the 22 builds across the city (the out of level hub)
It encompasses all of the Pixar Builds and I (Incredibles) Family Builds which are mainly unlocked by completing crime waves. Crime wave completion leads to the entire district markers opening up and otherwise hidden build sites appearing.
One thing to note: I had an issue with the last build showing up. It was in the finacial district and was the last pixar build needed as well. I flew back to previous pixar build, opened it up to receive a purple stud, and flew back to the finacial district and it appeared. It would seem moving a significant amount of distance away from the build site sort of resets it.
Lastly, bare in mind there is currently a bug with achievements and rest mode on your xbox. Do not do the last build after coming back from rest mode and not fully quiting your game. Completion of the last build this way will render the achievement unobtainable in 1 playthrough.