Back in the mid 1980's, I was on trip to Houston so stopped by the Johnson Space Center which had one of the three remaining Saturn V's on display outside. Being a space nerd, I spent a solid hour checking out the Saturn. When you got up close, the amount and severity of the corrosion apparent under the paint was simply shocking. That was only ~15 years since it had been flight worthy. I shutter to think what aluminum structure would be like after being outside - unmaintained - for over 50 years.
BTW, a few years after I saw that Saturn V, it was restored and moved into an indoor facility where it remains today (although I haven't been back to Houston to see it since). I donated a some money to the fundraising to pay for the restoration.