Maintenance-free siding doesn't last forever. I suspect that they did this sometime in the late '50s/early 60's. It's been painted at least once, and not well. And it's white. And there's something about white paint on aluminum that gathers soot and bonds it on the molecular level so the only way to get the soot off is to strip the old paint with a power washer to get it down to the bare aluminum, then re-prime and repaint.
This year, the aluminum is getting replaced with vinyl. Most of the house anyway. The exception is the front and the breezeway-- the front because I had the siding torn off to work on the porch, and the breeezeway because I had replaced that with vinyl quite some time ago, when the garage was torn down.
The front is weird-- I've mentioned the facade, which is capped with some formed galvanized steel that was molded to look sort of like crown molding. The zinc has long since been eaten away, and it's rusting, which essentially means it's not recoverable as the rust has gotten inside the heart of the steel. I need to replace those caps with something more durable, something that won't rust or decay until I'm long gone.
I'm already planning on doing faux stone veneer on the front. The amount of stone vs. something else (either stucco or vinyl or cedar) is yet to be determined, but the caps need to be done regardless. I'm considering whether doing them in faux stone would be a good idea-- they'd be heavy as hell, but they'd be durable. And they'd look cool. Plastic is an option, but I'd have to build them up from pieces and "weld" them together. Aluminum and steel are right out-- I might do an aluminum flashing underlayment simply for good construction practice, but the actual decorative piece that covers it needs to be architecturally sound.
There is fiberglass. Or kevlar, or carbon-fiber composites, all done similarly enough that the process is the same. Light, strong, weather-resistant. Expensive, but maybe worth it.