Drones and infrared provide for the ability to essentially get a "chest x-ray" of the roof. Non-invasive diagnostic studies can provide valuable insight not visible to the naked eye.
Roof top living is the next back yard of the times. A creative and beautiful way to expand the living space of your building is on the roof. Don't forget that it's still a roof though, for complacency in sound waterproofing here can be costly.
Going solar, in Style.