For instance, the upgrade to Level 2 requires 5 Cement Trucks, 5 Elevators and 5 Cast Iron Plates. The Cement Trucks and Elevators are earned through general news posts on your wall while the Cast Iron Plates are earned by sending individual requests to friends. When you finish this first upgrade, your Skyscraper Residence will offer a population of 300-500 citizens and will offer 323 coins in rent every day (at its basic Level 1 state, it offers just 100 citizens in population).
As you upgrade the building by collecting more parts, these stats will increase. If you can make it all the way to Level 6, you'll be left with a much larger and much more impressive building visually that offers 4,500 citizens in population and 545 coins a day in rent. If, for whatever reason, you decide to delete the Skyscrapers from your town, you can rebuild them at the same state you left them later on. That is, you won't have to upgrade from Level 1 all over again.
Unfortunately, you can't have anymore than one set of towers in your town, so once you've fully upgraded this particular structure, you'll be left adding citizens to your town the old fashioned way. Still, this building is a great boost in your overall population, especially if you're short on space, so I'd definitely suggest building it. As you do, you'll also be able to work on an accompanying quest that will give you 1 million coins as its reward (just be warned - it's definitely not an easy quest to complete)!
What do you think of this Skyscrapers feature in CityVille? Will you build this upgradeable project in your city, or are you still working on too many other things right now? Sound off in the comments.