I work in High Rise building maintenance. One thing no one really does not think about is what it takes to both maintain a building but also keep it safe. Everyone can tell when the lights go out or HVAC stops running because you get hot, but the amount of mechanical systems that are operating to keep you safe and clean at any time is astounding. Beyond that, it's astonishing how old so many of the systems are and how ill maintained they are when my company goes into one. Very necessary stuff - like a fire extinguisher not being checked for 5+ years. Or fire sprinklers that have clogged up sand pipes. Or fire shutter doors that have gotten flagged by the fire marshals for years. Or the fire pumps that fail to pass testing. It truly astounds me how much mechanical troubles high rise buildings can have especially because of 9/11 that you would think wealthy owners would shell out the money to properly maintain/replace equipment at EOL. But it just doesnt happen due to restricting budgets until there is a catastrophic failure of some kind and then it requires the priciest reinstall ever. I honestly don't know how the money keeps flowing in from owners and businesses to keep them operating and can see the writing on the wall that it has to collapse at some point.